My car was doing something similar. After having the harmonic balancer replaced some weeks ago (see harmonic balancer posts on this site), my car started to act a little funny. After driving it with the A/C blowing full and kind of driving it a little hard, I would come home, put it in park and then my car would start to idle high. It's done this before, and I simply revved the engine a couple of times and it stopped. This time it didn't do that though. So, I turn off the engine and then turn it back on and it's back to its normal idle. After freaking out for a bit, I decided to mess around with the throttle under the hood to see if it was sticking, but it seemed fine to me, then I noticed that my coolant reserve was completely bone dry. Now, this seemed pretty odd because when I had taken my car in to have the harmonic balancer replaced, they had flushed my coolant system and whatnot, so I thought it was really weird that my reserve was empty. I have not noticed any sort of leaks under my car, so that added to my confusion. So, I added more coolant and my car hasn't done the idle thing since. So, I'm wondering if any of you monkey wrencher guys can help this chick figure out why the hell my car is so damn temperamental. Oh, by the way it's a 1994 Ford Tempo. Thanks guys!