I just did this last weekend. I have 130,000 miles and I was chasing a very minor idle issue. After long highway trips, it will sometimes slightly stumble at idle. Sooooo, last weekend, I pulled the throttlebodies and cleaned them (off the car, btw.) I also replaced the pcv valve and rubber hose (it was shot.) Then I cleaned the idle air controller too. It had some amount of buildup on it, but its all clean now.
When I first started it, it shot up to 2-3000 rpm, then quickly dropped. On the trip into work this morning, I noticed that its behaving like the throttle is sticking (although I don't think it really is.) Now, when I step off the gas on the highway, its like the return spring is weak. Perhaps I re-assembled the damn spring on the throttle synchronizer shaft incorrectly. The service manual does not show a good picture of it. Anyone out there got a good photo of theirs (3.5L, btw.)
I am wondering if its mostly that the computer must learn to deal with a clean intake and is just in the "figuring it all out" process. I am considering pulling the pos wire on the battery and letting it sit, but I don't want ot lose all my radio stations if I don't have to.
Does this condition fix itself ??