2003 impala stuck accelerator..

Your vehicle does not have a idle air control valve , don't know how you came up with that .(code reader ? ) Your vehicle has what is called drive by wire - electronic throttle control . Or as GM calls their system TAC - throttle actuator control .

Throttle Actuator Control (TAC) Overview
The throttle actuator control (TAC) system uses vehicle electronics and components to calculate and control the position of the throttle blade. This eliminates the need for a mechanical cable attachment from the accelerator pedal to the throttle body. This system also performs the cruise control functions as well.
The TAC system components include, but are not limited to, the following:
• The accelerator pedal position (APP) sensors
• The throttle body assembly
• the engine control module (ECM)
The APP sensors and the throttle body assembly provide inputs to the ECM to ensure accurate calculations and control of the TAC system.
Accelerator Pedal Position (APP) Sensor
The APP sensor is mounted on the accelerator pedal assembly. The APP is actually 2 individual APP sensors within 1 housing. These are 2 separate signal, low reference, and 5-volt reference circuits. The APP sensor 1 voltage increases as the accelerator pedal is depressed. The APP sensor 2 voltage also increases as the accelerator pedal is depressed, but the voltage range for sensor 2 is approximately half of sensor 1.


Your best bet mite be to take it to a qualified repair shop that has the right diagnostic tools to find the problem .

https://www.youtube.com/watch?v=x4xcQSRAgFI

https://www.youtube.com/watch?v=oPPLAHSSluw

Because your vehicle has electronic throttle control an it need's to be calibrated . How are you resetting the computer ? scan tool , disconnect the battery ? Why did you reset the computer ?
2004 PCED On Board Diagnostics SECTION 1: Description and Operation Procedure revision date: 09/16/2004 Torque Based Electronic Throttle Control (ETC)
Overview
The Generation II (Gen II) Torque Based Electronic Throttle Control (ETC) is a hardware and software strategy that delivers a transmission output shaft torque (via throttle angle) based on driver demand (pedal position). It utilizes an electronic throttle body, the PCM and a accelerator pedal assembly to control throttle opening and engine torque. The ETC system basically replaces the standard cable operated accelerator pedal, idle air control (IAC) motor, 3-wire throttle position sensor (TPS) and mechanical throttle body .
Background "Why Torque Based ETC"
Torque based ETC enables aggressive automatic transmission shift schedules (earlier upshifts and later downshifts). This is possible by adjusting the throttle angle to achieve the same wheel torque during shifts, and by calculating this desired torque, the system prevents engine lugging (low RPM and low manifold vacuum) while still delivering the performance and torque requested by the driver.
It also enables many fuel economy/emission improvement technologies such as:

• VCT (deliver same torque during transitions)
• Hybrid Electric Vehicle (HEV)

Torque based ETC also results is a less intrusive vehicle and engine speed limiting, along with smoother traction control.
Other generic benefits of ETC are:

• Eliminate cruise control actuators
• Eliminate Idle Air Control (IAC) Bypass actuator
• Better airflow range
• Packaging (no cable)
• More responsive powertrain at altitude and improved shift quality

It should be noted that the ETC system includes a wrench light on the instrument cluster that illuminates when a fault is detected. Faults are also accompanied by DTCS and the "Check Engine Soon" light.
Electronic Throttle Body (ETB)
The Gen II electronic throttle body (Figure 133) has the following characteristics

1. The DC motor is driven by the PCM (requires two wires). The gear ratio from the motor to the throttle plate shaft is 17:1.

1. There are two designs; parallel and in-series. The parallel design has the motor under the bore parallel to the plate shaft. The motor housing is integrated into the main housing (in general this is more difficult to package). The in-series design has a separate motor housing that protrudes out and offers more packaging flexibility.

1. Two springs are used: one is used to close the throttle (main spring) and the other is in a plunger assembly that results in a default angle with no power applied. This is for limp home reasons (force of plunger spring is 2 times stronger than the main spring). Default angle is usually set to result in a top vehicle speed of 30 MPH (48Km). Typically this throttle angle is 7 to 8 degrees from the hard-stop angle.

1. The closed throttle plate hard stop is used to avoid the throttle from binding in the bore (~0.75 degree). This hard stop setting is non-adjustable and is set to result in less airflow than the minimum engine airflow required at idle.

1. Unlike cable type throttle bodies, the intent for the ETB is not to have a hole in the throttle plate or to use plate sealant. The hole is not required in the ETB because the required idle airflow is provided by the plate angle in the throttle body assembly. This plate angle controls idle and idle quality and eliminates the need for IAC bypass actuator.

1. The system has two throttle position sensors. Redundant throttle position signals are required for monitor reasons. TP1 has a negative slope (increasing angle, decreasing voltage) and TP2 has a positive slope (increasing angle, increasing voltage). During normal operation the negative sloped TP sensor (TP1) is used by the control strategy as the indication of throttle position. The TP sensor assembly requires four wires.

• 5 V Reference Voltage
• Signal Return (ground)
• TP1 voltage with negative voltage slope (5-0)
• TP2 voltage with positive voltage slope (0-5)

Accelerator Pedal Position Sensors (APPS)
The ETC strategy uses pedal position sensors as an input to determine the driver demand.

1. There are three pedal position sensors required for system monitoring. APP1 has a negative slope (increasing angle, decreasing voltage) and APP2 & APP3 both have a positive slope (increasing angle, increasing voltage). During normal operation APP1 is used as the indication of pedal position by the strategy.

1. There are two VREF wires, two signal return wires and three signal wires (total of seven wires and pins) between the PCM and APPS assembly.

• 2- 5 V Reference Voltage
• 2- Signal Return (ground)
• APP1 voltage with negative voltage slope (5-0)
• APP2 voltage with positive voltage slope (0-5)
• APP3 voltage with positive voltage slope (0-5)

1. The pedal position signal is converted to pedal travel degrees (rotary angle) by the PCM. The software then converts these degrees to counts, which is the input to the torque based strategy.

1. The three pedal position signals ensure a correct input to the PCM, if any one signal has a fault. The PCM knows if a signal is wrong by calculating where it should be, inferred by the other signals. A value will be substituted for a faulty signal if two out of the three signals are bad.

Check the timing. Sounds like its off.

Problem with the electronic throttle control .
It should be noted that the ETC system includes a wrench light on the instrument cluster that illuminates when a fault is detected. Faults are also accompanied by DTCS and the "Check Engine Soon" light. Your best bet is to take your vehicle to a reputable ASE certified repair shop .
Overview The Generation II (Gen II) Torque Based Electronic Throttle Control (ETC) is a hardware and software strategy that delivers a transmission output shaft torque (via throttle angle) based on driver demand (pedal position). It utilizes an electronic throttle body, the PCM and a accelerator pedal assembly to control throttle opening and engine torque. The ETC system basically replaces the standard cable operated accelerator pedal, idle air control (IAC) motor, 3-wire throttle position sensor (TPS) and mechanical throttle body .

It should be noted that the ETC system includes a warning indicator (wrench light) on the instrument cluster that illuminates when a fault is detected. Faults are accompanied by DTCs and may also illuminate the malfunction indicator lamp (MIL).
Torque Based Electronic Throttle Control (ETC)
Overview
The Generation II (Gen II) torque based electronic throttle control (ETC) is a hardware and software strategy that delivers an engine output torque (via throttle angle) based on driver demand (pedal position). It uses an electronic throttle body, the PCM, and an accelerator pedal assembly to control the throttle opening and engine torque. The ETC system replaces the standard cable operated accelerator pedal, idle air control (IAC) valve, 3-wire throttle position sensor (TPS), and mechanical throttle body.
Torque based ETC enables aggressive automatic transmission shift schedules (earlier upshifts and later downshifts). This is possible by adjusting the throttle angle to achieve the same wheel torque during shifts, and by calculating this desired torque, the system prevents engine lugging (low RPM and low manifold vacuum) while still delivering the performance and torque requested by the driver. It also enables many fuel economy/emission improvement technologies such as variable cam timing (VCT) (deliver same torque during transitions).
Torque based ETC also results in less intrusive vehicle and engine speed limiting, along with smoother traction control.
Other benefits of ETC are:

• Eliminate cruise control actuators.
• Eliminate idle air control (IAC) valve.
• Better airflow range.
• Packaging (no cable).
• More responsive powertrain at altitude and improved shift quality.
• DO you know what electronic throttle control is ?

014 Electronic Throttle Operation

Your vehicle has electronic throttle control . Position sensor's in the gas pedal an the throttle body , inputs to the Throttle Actuator Control Module
The TAC module is the control center for the throttle actuator control system. The TAC system is self-diagnosing and provides diagnostic information to the PCM through a dedicated serial data line. The TAC achieves throttle positioning by providing a pulse width modulated voltage to the TAC as directed by the PCM.

The throttle actuator control (TAC) system delivers improved throttle response and greater reliability and eliminates the need for mechanical cable. The TAC system performs the following functions:
• Accelerator pedal position sensing
• Throttle positioning to meet driver and engine demands
• Throttle position sensing
• Internal diagnostics
• Cruise control functions
• Manage TAC electrical power consumption
The TAC system components include the following:
• The accelerator pedal position (APP) sensors
• The throttle body assembly
• The throttle actuator control module
• The powertrain control module (PCM)
Accelerator Pedal Position (APP) Sensor
The accelerator pedal assembly contains 2 individual APP sensors within the assembly. The accelerator pedal position (APP) sensors 1 and 2 potentiometer type sensors each with 3 circuits:
• A 5-volt reference circuit
• A low reference circuit
• A signal circuit
The APP sensors are used to determine the pedal angle. The control module provides each APP sensor a 5-volt reference circuit and a low reference circuit. The APP sensors then provide the control module with signal voltage proportional to pedal movement. APP sensor 1 signal voltage is low at the rest position and increases as the accelerator pedal is applied. APP sensor 2 signal voltage is high at the rest position and decreases as the accelerator is applied.
Throttle Body Assembly
The throttle body assembly consists of the throttle body, the throttle position (TP) sensors, and the throttle actuator motor. The throttle body functions similar to a similar to a conventional throttle body with the following exceptions:
• An electric motor opens and closes the throttle valve.
• The throttle blade is spring loaded in both directions and the default position is slightly open.
• There are 2 individual TP sensors within the throttle body assembly.
The TP sensors 1 and 2 are potentiometer type sensors each with 3 circuits:
• A 5-volt reference circuit
• A low reference circuit
• A signal circuit
The TP sensors are used to determine the throttle plate angle. The control module provides each TP sensor a 5-volt reference circuit and a low reference circuit. The TP sensors then provide the control module with signal voltage proportional to throttle plate movement. Both TP sensor signal voltages are low at closed throttle and increase as the throttle opens.

Flickering light's could be caused by a bad diode in the alternator . Fluctuating idle could be caused same alternator problem or dirty throttle plate.
Throttle Body Cleaning To Restore Idle Quality

Idle Air Control Valve Pintle may be bad If you disconnect the IAC and the problem ceases it can point to this being the problem.: Removal & Installation 3.5L Engine To Remove:

1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
2. Remove the fuel injector sight shield.
3. Drain the cooling system.
4. Remove or disconnect the following:
   • The air cleaner intake duct. Figure of IAC and TPS electrical connectors disconnected.
     
     
   • The idle air control (IAC) valve and throttle position (TP) sensor electrical connectors. Figure of cruise control and throttle control cables removed from throttle lever.
     
     
   • The cruise control cable and throttle control cable from the throttle body lever.
   • The fuel pressure regulator vacuum hose, positive crankcase ventilation (PCV) hose and the throttle body vacuum port hose.
   • The throttle body coolant hoses.
   • The throttle control cable bracket, leaving the throttle and cruise cables connected.
   • The upper nut holding the throttle body to the intake manifold.
   • The throttle body assembly.
5. Clean the gasket mating surfaces.

To Install:

1. Install a new gasket and new studs if necessary.
2. Install or connect the following:
   • The throttle body assembly.
   • Start the top nut by hand.
   • The throttle body coolant hoses.
   • Position the throttle control cable bracket and hand start the retaining nuts and bolt.
   • Torque the three throttle body retaining nuts to 89 in.lbs. (10 Nm). And the bracket retaining bolt to 115 in.lbs. (13 Nm).
   • The throttle body vacuum port hose, PCV valve hose and the fuel pressure regulator hose.
   • The throttle control and cruise control cables to the throttle body lever.
   • The IAC valve and TP sensor electrical connectors.
   • The air intake duct.
3. Refill the cooling system.
4. Install the fuel injector sight shield.

4.0L Engine To Remove:

1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
2. Relieve the fuel system pressure.
3. Remove or disconnect the following:
   • Negative battery cable.
   • The Mass Air Flow (MAF) sensor electrical connector.
   • The air cleaner intake duct.
   • The PCV valve fresh air tube. Figure of cruise control cable removed from throttle cable bracket.
     
     
   • The cruise control cable and throttle control cable from the bracket.
   • The cruise control cable and throttle control cable from throttle body lever. Figure of IAC valve and TPS connectors removed.
     
     
   • The idle air control (IAC) valve and throttle position (TP) sensor electrical connectors. Figure of fuel lines removed from retainer on throttle cable bracket.
     
     
   • The fuel feed and return lines from the retainer on the throttle control cable bracket.
   • The transaxle shift cable clip from the throttle control cable bracket. Figure of throttle body removed from water crossover.
     
     
   • The throttle body from the water crossover.

To Install:
NOTE: The Mass Air Flow (MAF) sensor inlet and the outlet of the air cleaner assembly must line up when installed. Misalignment may cause MIL illumination or driveability concerns.

1. Install or connect the following.
   • The throttle body to the water crossover. Torque the bolts to 106 in.lbs. (12 Nm).
   • The IAC valve and TP sensor electrical connectors.
   • The throttle and cruise control cables to the throttle body lever.
   • The throttle and cruise control cables to the throttle control cable bracket. The transaxle shift cable clip to the throttle control cable bracket.
   • The fuel feed and return line retainer to the throttle control cable bracket.
   • The MAF sensor electrical connector.
   • The air cleaner intake duct clamp. Torque the clamp to 27 in.lbs. (3Nm).
   • The PCV valve fresh air tube.
   • The fuel injector sight shield. Torque the nuts to 20 in.lbs. (2.3 Nm).
2. Install the negative battery cable.
3. Pressurize the fuel system and verify no leaks.

Clean out your throttle body, the IAC (idle air control) valve may be sticking from carbon build up. You can get a can of throttle body cleaner at Auto Zone or most auto parts store and follow the instruction on the can.

Make sure you use all of the can and you may want to do it twice with two cans of throttle body cleaner just get it all cleaned out. The IAC controls the amount of air enters the engine to get it started and to idle smoothly with the different loads. A stuck IAC valve will give issues to what you have described.

Thank you for using fixya and be safe.

This is a dangerous defect. What you want to do is isolate the Cruise cable from the Throttle mechanism. Then get the Cruise cable away from the Throttle so it can not jam the Throttle accidentally.

With the engine OFF use your hand and move the remaining Throttle mechanism and feel for sticking or roughness in the control. If you feel binding, start removing the connection of the Throttle cable and work your way through all the moving parts like a Butterfly flap on the Airhorn, the TPS (throttle position sensor) and so on until you find out what is rubbing.

It is possible that the Cruise was disengaging because the Throttle parts were binding. If disconnecting the Cruise eliminates the sticking throttle, then all the problems came from the Cruise control cable or the Cruise Box. Once you have made a thorough check of the Throttle you can blame the Cruise for your problems and replace the parts.

Vacuum leak or fast idle sensor inside throttle body. Also check to make sure throttle cable and cruise control cable is not out of place on the cable roller/pulley on top of intake manifold.