Your issue is likely the Idle Air Control Valve (IACV). It rests on top of the throttle body and is easy to replace - - just has two 8mm bolts, a gasket, and a small wire clip. If you remove the IACV, look inside. If it is black with soot, likely it needs replacement.
Since your check engine light did illuminate, it wouild be wise to get the exact codes. There may be other things hidden. Remember the car computer is not a tell-all, and just because the code says there is a fault, it doesn't mean that replacing the part which the computer says is malfunctioning is the cure.
But in most cases with the IACV, just replacing it is the cure.
Other reason for a high idle is a really bad vacuum leak. Check the PCV grommet connection and brake booster hose. Remove hose from brake booster and plug it with your thumb to test it.
Sunday, December 21st, 2008 AT 7:28 PM