if his car isnt idling correctly there is an air bypass screw that can be adjusted to tweak up the idle on the throttle body. its dow the hole just above the throttle linkage. theres also an adjustment screw on the AFM. it could also be needing a wee adjustment to tweak the idle mixture.
if you put the silver iac valve on the car will idle at 4000RPM (oops, i tried this cos my mate was showing off to me how he could drive around without ever touching his throttle, gettin up to about 20 in 5th without stalling or touching throttle, so i thought i gotta get me one of those valves but it didn`t work out like that. the joys of bein young and inexperienced )
the one by the throttle mate. i have never messed with one, but i get a lot of mail about how the car now idles badly and it drives like crap lmao
i thought it adjusted the air intake full stop, it can control idle, but also leaks that amount of air at all revs. never really thought about it, i just said put it back and they said thanks its fine now. (more often than not a lot of other stuff had been fiddled with in addition)