Once in a while when the car is at rest the rpms oscillate between 1000 to 2000. This only happens on occasion and it seems more prevalent after a trip on the highway. If I turn the car off and back on the rpms remain constant at 800. I suspect it is a timing issue, any suggestions. Thanks for your help

 

try adjusting the throttle position sensor, the cars picky about that, so if its off by a little the computer gets cunfused



mike