First of all thanks to everyone here who helps us DIY'ers. My 2000 LS 3800II has been revving high RPM's at start up and during idling at city stop lights, signs, and so forth. Not all the time. 50% of the time she will return to normal idle but don't see a coorelation when the engine is hot or cold. I replaced the IAC and that helped a little. I don't see a vacuum leak and the pintle on the EGR is fine. I cleaned the throttle body plate when I saw carbon build up. She has just over 250K on her and I want to keep her running. Any ideas? Thanks for you help.