Ok, so new IAC, new plugs, and cleaned tb. After all this I get an idle of about 12-1500rpms. If I'm driving I get the dreaded hanging idle at about 2000rpms. I even put on the IAC restrictor plate the Ford sold for a while, closed the adjustment screws all the way, and still have the idle problem. But if I unhook the IAC the engine runs great other than the CEL. When first started it stumbles a little but after that it's fine. Anyone have a clue what I might be seeing? Like I said, it didn't start until I changed spark plugs and cleaned the tb. It's not a vacuum leak, I already checked with ether, and no surges anywhere. Could, if I gapped incorrectly, spark plug gap cause this? Or cleaning my tb cause it? Never had a problem before now.
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C&L 80mm mass air and True Flow pipe, Mac CAI, BBK 65mm tb, Steeda non-piggy back ud pulleys, MGW shifter, RAM HD clutch and aluminum flywheel, 3:73 gears, 2.5" Dynomax o/r x pipe, 3" MAC cat back system w/ 3 1/2" tips, Kenny Brown(front and rear strut tower brace, caster plates, subframe connectors,extreme matrix brace,jacking rails, torque brace, lowering springs), Bilstein shocks, 03-04 Cobra(side scoops, rear bumper cover, top), 6pt roll cage, white FR500's, FMS 2000 Cobra R air dam.
89 mustang gt,3.73,flomasters with xpipe,70mm trottle body,70mm egr spacer,cobra upper and lower intake,msd ignition cap wires and button,underdrive pullys, 180 degree stat,bbk cold air intake, hurst shifter,aluminum driveshaft,and lots more
if u took the throttle body off to clean it u might have to readjust ur tps sensor to get the right voltage
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89 mustang gt,3.73,flomasters with xpipe,70mm trottle body,70mm egr spacer,cobra upper and lower intake,msd ignition cap wires and button,underdrive pullys, 180 degree stat,bbk cold air intake, hurst shifter,aluminum driveshaft,and lots more
After 93 you would have to of modified our TPS, drilling out the holes, on our TPS to adjust them.
You cleaned your MAF right?
What did you gap your plugs at? but i dont' think that's the problem though.
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1995 Mustang GT-Heavily Modded-Sold 2003 Ford Lightning-Sold 1997 Saleen-5.4 conversion-Sold 2005 Mustang GT-Torch Red-Sold 2003 Mustang Cobra-Oxford White 2003 4Runner V8 Sport Edition 4X4
Exact same problem I had in my 95. Couldn't figure it out, no matter what I tried. Then a guy at a local performance shop cleaned my MAF. Ran like a champ. Might give that a shot, it's a pretty common problem
Still having idle problems 
