how might a bad IAC valve behave? mine is acting wierd, if i start the car it will idle around 1100 then slowly drop to ~600-700, then when ever i press the gas it will do it again...but if i unplug the IAC it idles constant 700....so is my IAC bad?
Well the IAC is working when you start the engine.. Pretty much its main purpose.. If you unplug it the engine should stall out and not continue running.. I would say its bad, usually if you unplug and try to start to the engine it will try to run and then stall.. You can take it off and check the valve if it looks like there is alot of carbon build up in there you can try to clean it out and it could help.. if not replace it..