Yes, for a dry manifold they sure do gunk up. My Taurus SHO engine has 12 runners and it took something like four cans of carb cleaner and some rubbing to get the gunk out. Throttle body was also gunked up.

I seem to remember a thread a few years ago about aftermarket Idle Air Control valves not lasting a long time.

On the original IAC valve, first you check it for having continuity, then if it does, get after the working parts with carb or fuel injection cleaner.

Really there's nothing to go wrong with an IAC valve, except having an open circuit in the solenoid coil, and the need for cleaning every blue moon.

R.