I have a 89 iroc 350 tpi.the car runs pritty good except when im only a quater way on the gas it runs real rough almost like its hesitating for some reason but if i drop it to the floor its a lot smoother and takes right off if anybody can throw some advice this way it would be very helpfull.

 

Sounds like it might be a sticking injector. If you can, run the injector balance check.