While driving fine at low speed it shook and engine began to run really rough and idled low. it contiues to start runs good for 3 seconds and begins to be rough again. in park idles rough, giving it gas it stuggles between 1000-2000 rpm. between 2000-4000 it is smooth. ???

HI
first I would like to tell you, do this procedure only if the 5th digit of your VIN is C or K.

Description

The engine control module (ECM) learns the idle position of the throttle plate to ensure the correct idle. Anytime the throttle body is cleaned or replaced, the ECM must learn the new throttle position. The idle may be unstable or a DTC may set if the throttle position is not learned.

Conditions for Running the Throttle Learn Procedure

• DTCs P0101, P0102, P0103, P0107, P0108, P0111, P0112, P0113, P0506, and P0507 are not set.

• The engine speed is between 450-4,000 RPM.

• The manifold absolute pressure (MAP) is greater than 5 kPa.

• The mass air flow (MAF) is greater than 2 g/s.

• The ignition 1 voltage is greater than 10 volts.

Throttle Learn

Important: Do NOT perform this procedure if DTCs are set. Refer to Diagnostic Trouble Code

(DTC) List - Vehicle.

1. Start and idle the engine in PARK for 3 minutes.

2. With a scan tool, monitor desired and actual RPM.

3. The ECM will start to learn the new idle cells and Desired RPM should start to decrease.

4. Ignition OFF for 60 seconds.

5. Start and idle the engine in PARK for 3 minutes.

6. After the 3 minute run time the engine should be idling normal.

Important: During the drive cycle the check engine light may come on with idle speed DTCs. If idle speed codes are set, clear codes so the ECM can continue to learn.

* If the engine idle speed has not been learned the vehicle will need to be driven at

speeds above 70 km/h (44 mph) with several decelerations and extended idles.

7. After the drive cycle, the engine should be idling normally.

* If the engine idle speed has not been learned, turn OFF the ignition for 60 seconds

and repeat step 6.
8. Once the engine speed has returned to normal, clear DTCs.
Good Luck

There could be all sorts of problems considering the age of the vehicle from electronic to engine valve seats and only a back to basics approach can fully evaluate the situation - lots of checking and lots of time...

A rough idle could mean a misfire confined to just one or two cylinders or it could be a couple of cylinders that are working but inefficient or it could all be intermittent.

If the car was mine I would begin by removing the injectors and having them checked and if any swarf is found inside it will place a question mark over the high pressure pump.

Should be on or near the fuel injector supply rail.

True of many cars. Happened to me too many times, fourin
or domestic.

If your car has a mas air flow sensor (usualy located right aroung air filter or in air passage after the air filter) check and clean the sensor. This looks like a small spring on the end of 2 wires. BE CAREFUL not to damage the sensor. I have seen where the sensor gets dirty over time and this can cause a rough idle.

Sounds like possible vacuum leak. Next time it starts try spraying starting fluid around vacuum hoses, if engine speeds up, there is a vacuum leak at that point where you sprayed. Hope this helps.

Possible Idle air control, simple to change on the throttle body

0340 is camshaft position sensor and the other 0325 is the knock sensor. Chances are you need to replace the sensors and good to go.

Just trowing some suggestions out there, but, I would check the idle air control valve (solenoid) or the throttle position sensor. If they check out then my last guess would be the map sensor or the vaccuum to the map sensor. Hope I was able to help. Best wishes.

WEll it is possible it could be the idle air control. one the most comon problems is the fuel pressure regulator. To check it find the fuel rail the fuel regulator will have one vacuum hose on it remove the hose and check to see if it is wet with fuel if not have some one trun the key on or start the car if it leaks fuel out the regulator is bad. This would explain why its hard to start when it sits because it floods out the motor