captahab

I have a 86 LX, Flowmaster w/cats, BBK Headers,Cobra upper and lower,b303 cam,ported and polished stock heads,MDS ignition,changed to MAF and no smog, 2.73 gears. I bought the car used and those are the mods that Im aware of to date. The car runs really well except when you down shift from 2nd to 1st the car wants to die. I removed and cleaned the IAC. I also cleaned the throttle body and the MAF Sensor. None of the above looked dirty to me. I also cleaned the air filter and the inlet hose coming from the ram air under the bumber.
Im not sure what direction to go at this point. Im thinking about purchasing a new IAC, maybe the current one isnt working at random ?
Any suggestions would be appreciated.......