Toyota corona my toyota corona with s3 engine has problem,if i used air conditioning the RPM drop and late response for idle-up

run the fault codes as the engine idle is being affected by a faulty sensor . The vibrations are probably because the idle rpm's are too low.

What's happening is, the engine is under increase load when the A/C is running. Typically there is a solenoid (near the throttle linkage) that controls idle speed when the A/C compressor (clutch) is engaged. It activates each time the compressor cycles on to regulate the system. If idle returns to normal when A/C clutch is disengaged (or A/C is off), then the solenoid or some signal that controls the solenoid to maintain the idle is the likely to be the problem. e.g. The solenoid fuse maybe blown. This might be a good place to start investigating the problem. Best of luck resolving this problem.

Check out related help links to troubleshoot these problem:----Click the link below:---Idles Fine but RPM jumps in drive mode? http://technoanswers.blogspot.in/2012/07/idles-fine-but-rpm-jumps-in-drive-mode.html
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These will help.
Thanks.

IDLE SPEED COULD BE TOO LOW.IDLE SPEED SHOULD BE 800 RPM. IF IDLE SPEED TOO LOW AND ENGINE NOT WELL TUNE UP AIR CONDITIONER WILL PUT LOAD ON ENGINE CAUSE ENGINE OVER HEAT AND SHUT OFF.

Most trucks and car will idel about 1500 to 2000 rpm until they. Are warmed up. Its a warm up feature

Idle Air Control (IAC) Valve OPERATION The ECM is programmed with specific engine speed values to respond to different engine conditions (coolant temperature, air conditioner on/off, etc.). Sensors transmit signals to the ECM which controls the flow of air through the bypass of the throttle valve and adjusts the idle speed to the specified value. Some vehicles use an Idle Speed Control (ISC) valve while others use an Air Valve (AV) or Idle Air Control (IAC) valve to control throttle body by-pass air flow. TESTING 2S-ELC Engine

1. With the engine running and the coolant temperature below 140°F (60°C), pinch off the Air Valve hose and verify that the idle is reduced by no more than a 100 rpm.
2. Unplug the valve wire connector and measure the coil resistance with an ohmmeter. It should be 40-60 ohms with the coolant temperature at 176°F (80°C) and the air valve closed.
3. If not as specified, replace the valve. 3S-FE and 5S-FE Engines NOTE: The idle speed must be set correctly before testing the ISC valve.
   
4. Bring the engine to normal operating temperature with transmission in N.
5. Using a jumper wire, connect the terminals TE1 and El of the check connector (DLC 1). Fig. 1: Attach a jumper wire to the terminals TE1 and E1 in the DLC 1
   
   
6. The engine rpm should rise to 900-1300 rpms for 5 seconds. Check that it returns to idle speed. If rpm is as specified, the valve is functioning properly.
7. If rpm did not function as specified, stop the engine and disconnect the jumper wire.
8. Disengauge the ISC valve connector.
9. Using an ohmmeter, measure the resistance between the +B terminal (middle terminal) and the ISC1 - ISC2 (3S-FE) and the ISCC - ISCO (5S-FE) outer terminals. Fig. 2: Attach an ohmmeter and measure the resistance between the three terminals - 3S-FE engine
   Fig. 3: Attach an ohmmeter and measure the resistance between the three terminals - 5S-FE engine
   
   
10. The resistance should be 16-17 ohms on the 3S-FE engine and 19.3-22.3 ohms on the 5S-FE engine.
11. If not as specified, replace the ISC valve.

1MZ-FE Engine NOTE: The idle speed must be set correctly before testing the valve. Make sure the A/C is off during testing. Fig. 4: The IAC valve is attached to the lower portion of the throttle body

1. Bring the engine to normal operating temperature with transmission in N.
2. Using a jumper wire, connect the terminals TE1 and El of the check connector (DLC 1).
3. The engine rpm should rise to 1000 rpms for 5 seconds. Check that it returns to idle speed. If rpm is as specified, the valve is functioning properly.
4. If rpm did not function as specified, stop the engine and disconnect the jumper wire.
5. Disengage the ISC valve connector.
6. Using an ohmmeter, measure the resistance between the +B terminal (middle terminal) and the RSC and RSO outer terminals. Fig. 5: Attach an ohmmeter and measure the resistance between the three terminals - 1MZ-FE engine
   
   
7. The resistance should be 21-28.5 ohms on a hot engine.
8. If not as specified, replace the ISC valve.

2VZ-FE and 3VZ-FE Engines

1. Disengage the ISC valve connector.
2. Using an ohmmeter, measure the resistance between the B1 terminal (lower middle terminal) and the S1 or S3 (lower outer terminals), and between B2 terminal (upper middle terminal) and the S2 or S4 (upper outer terminals). Fig. 6: ISC terminal identification - 2VZ-FE and 3VZ-FE engines
   
   
3. If the resistance is not 10-30 ohms, replace the ISC valve.
4. Apply battery voltage to terminals B1 and B2 while repeatedly grounding S1, S2, S3, S4, S1 in sequence. Check that valve moves toward the closed position. Fig. 7: Testing the IAC using battery voltage to see if the valve will close-2VZ-FE and 3VZ-FE engines
   
   
5. Apply battery voltage to terminals B1 and B2 while repeatedly Grounding S4, S3, S2, S1, S4 in sequence. Check that valve moves toward the opened position. Fig. 8: Testing the IAC using battery voltage to open the valve - 2VZ-FE and 3VZ-FE engines
   
   
6. If valve does not function as specified, replace the ISC valve.

you need to replace the throttle position sensor on the intake.

the ac idle assist may be defective, if it's electric check the fuses if it's vachum operated check for vac. leaks. Also lube cables sometimes they stick Use wd-40 on the cables sparingly don't want dirt to stick to the cable.

If you dont have any trouble codes, this usually occurs when the idle air control valve (IAC) is going bad.

The "Tachometer" is the gauge that indicates the engine RPM. It is not unusual for the idling RPM to drop slightly when the air conditioner comes on. The air conditioner represents a fairly large load on the engine so when it starts, the RPM will drop slightly. When driving, you'll probably not even notice that the air conditioning is a load on the engine unless you're accelerating uphill, pulling a trailer or passing another vehicle while the vehicle is fully loaded. At idle, the Envoy's computer should detect the falling RPM and make adjustments in fuel delivery to bring the RPM back up.

In any case, it shouldn't be cause for alarm, unless the air conditioner is stalling the engine. If this is the case, you are probably in need of service. The issue of low cooling from the air conditioner while idling in gear (as is the case when stopped in traffic, etc.) is correctable free of charge at the dealership on certain vehicles as a result of a recall. Your dealer can tell you if your vehicle is affected or if there is other recall work pending on your vehicle based on the VIN.

I hope this helps!