I think this post is in the wrong section. The'll move this later on.

Anyway, what year is this vehicle? carburetor? tbi (Throttle body injector)? fi (fuel injector)?

I've encountered this problem before and here's what my recomendation.

Three things I want you to check.

1. Take out your IAC (Idle Air Control solenoid) which is located on the throttle body. Clean it with a throttle body cleaner and a brush. Clean the spot where the IAC goes in to the throttle body.
If that does not work you may have to replace the IAC $29.

2. The TPS (Throttle Position Sensor) also causes problem which is located below the IAC. The TPS at IDLE provides voltage value to the computer and that's what how computer determine the position of the throttle plate. If there is a dead spot on the TPS providing incorrect voltage then it will throw the computer a little bit. The TPS can't be cleaned and you just have to replace it $19.

3. The MAF (Mass Air Flow sensor usually located right after the air filter box) or ACT (Air Charge Temperature sensor usually located on the side of the air filter box). Try cleaning them with some throttle body cleaner and let it dry.

Check the connectors as well of all sensors.