My car now has the same problem and I am thinking its a vacuum leak from the IAC valve because I didnt install that spacer. A good way to check for a vacuum leak is to get a can of butane and spray the edges of the gaskets you want to check. If you have a leak the butane will get sucked into the block and cause your engine to rev noticeably. You have now pinpointed your leak. I am going to do this sat at the same time I install the IAC spacer.
Also, I want to say you guys have been awesome. I have learned so much coming to these forums its unbelievable! Thanks again!!!! :thumbsup: :thumbsup: