Gary: Yes, it has A/C, and it may be the IAC, but at the moment I don't think so. It seems to have something to do with the physical movement of the rotating assembly, even when everything seems to be clean and proper. I appreciate the offer the IAC test info, but I have the shop manual for 1997, which is what it is.

James70: At this point, I think we're going to have to replace the whole throttle body. Could also try a new IAC and/or TPS, but I'm reluctant to throw money blindly at new parts when the tests don't point that way. I'm sure the junkyard search engines will find you a TB assembly for the 22RE, too.

I don't think the dashpot would cause that for you, because the dashpot slows the closure of the throttle plate when you let off the gas, but should have no effect once the assembly has almost stopped rotating.

A mystery.

-Alex