I have a 96 LT1 stock I just replaced the IAC yesterday and i am still having the same sort of problems. When you hit the gas to WOT from a stop it hesitates so bad like it is going to stall and while driving hitting WOT it hesitates also but if you gradually give it gas it is fine. I cant figure out the problem someone told me it is the optispark acting up but i would like to narrow it down to that before ripping the motor apart.

If anyone has any help it is greatly appriciated thanks

 

Mine was doing the same thing....ended up being the 02s were bad and were grounding out somewhere along the connection.....My solution was simple...cut the wires to the O2s and unplug the rest of the wires...just a temp fix till I get off my *** and replace them

 

Is your throttle body dirty? If enough **** gets built up in the IAC passages it can make it hesitate. I'd recommend getting a TB gasket set and taking yours apart and cleaning it up inside. It's the cheapest most obvious fix. There are 3 gaskets. Top, bottom, and the one between the TB and manifold.

 

Check the rubber elbow between the MAF sensor and the throttle body for tears, or the bottom edge being off the throttle body.