The high idle is a vacuum leak somewhere in the system. You must find the leak first before trying to adjust the idle.
Then clean the throttle body and Idle Air Control valve.
The black plugs indicate a rich system, this will overheat the CAT and cause more problems. If it has been doing this for a while, check the CAT backpressure to see if it is already bad.
Tuesday, October 28th, 2008 AT 10:07 AM