Mustangkr500

I have a 1989 Ford Thunderbird Super coupe (3.8 of course) 118k miles 5sp manual, I am having an idle issue, I start the car warm or cold, and it starts but for a couple seconds it runs rough at about 500 rpm, then surges up to 2500 rpm and runs smooth though the smell of unburnt fuel is definately there, then when it is warmed up the car will drop down to about 1800 rpm and will not come down any further, the car seems to be running hot, thow im unsure if it is, it just has alot of heat coming out from under the hood after a short run, when the engine is reved up (3-5k rpm) it seems to be a little lagy on getting back down to 1800, thow it wips up to redline in the blink of an eye, boost pressure seems to be normal, In the process of testing things, i pulled the actual sensor out of the mass air unit and if i pulled it up about half way out of its hole in the metering tube while the engine was running, the engine would idle down pretty good, and if i pulled the sensor out of the aluminum housing completely the engine would drop to about 350-450 rpm and run rough (realy rough, barely at all). I am wondering what the most logical sensor or part to replace would be, i figure the mass air sensor may be contaminated or out of adjustment, the check engine light is not on, but does come on if i unplug the mass air sensor, i have unplugged both the tps and iac while the engine was running, doing so both times made the engine run rough.

I would really apreciate it if someone could help me out with this!?

Mustangkr500

UPDATE: I replaced the Idle air Control Valve/sensor which made the engine run great again, it was a 15 minute install and a world of difference, the only place i was able to find the idle air control valve was ebay Express, not regular ebay. I payed $50 for a new one plus i opted for fast shipping so for $68 i got a new one!