My engine constantly revs to 2k(3k while the engine's cold) when I'm in neutral. I've already replaced the IACv, the gaskets on the manifold and throttle body(as well as the whole I.M.), and the map sensor. My friend, who used to be a tech for honda, says it can't be the TPS for reasons unknown to me. A friend of his told him it could be the fast idle valve, and we're gonna go hose it down w/ some carb cleaner tomorrow and see what happens. I don't fully trust the IACv that i bought used off of ebay, but my friend does have a spare that he says works. If neither the spare IAC or cleaning out the fast idle doesn't work, does anyone have any idea what it could be?

A few notes. After replacing the I.M., it will kind of fix itself every now and then. Sometimes it will stop jumping and settle around 1500. Also, it tends to do the same thing for a little bit when I turn on the A/C.