Inspect and test the idle air bypass solenoid On top left side of engine.
November, 12, 2010 AT 7:04 PM
Need more info. Like when did it start doing this? Make sure gas pedal controls are not binding/damaged. Take rubber boot off throttle body and check butterfly plate for foreign objects that may keep it open. Look for any loose or broken vacuum hoses? Any intake manifold leaks will also cause high idle. Had a chevy that did the exact same thing and it was the intake gasket. The car backfired and blew the gasket out!
November, 12, 2010 AT 7:08 PM
Idle speed is controlled by the amount of air being allowed into the engine. If the idle is too high you have to look for unmetered air getting into the engine somehow. Vacuum leaks are the first place to check. You also want to look at temp sensors. If the computer things it's very cold out, it will increase the idle speed.