Gm 3800 v6 engine iac problem?

My 2002 grand prix gt keeps idling extremly high. if found the iac was the problem becuase it was dirty, almost fell apart when i pulled it out, and i could change the idle by unpluging it and messing with its plunger length. I replaced it with a new one, followed all instructions, and had the previous error code deleted, but its still revs up way too high. i unpluged and reset the pcm, started it and it was fine, but once i press the throttle and rev it up, the idle may shoot anywhere from 1500 to almost 3000 rpm. I've tried test driving it, consulting the repair manuel, and everything else, but i'm stumped. please help, its sucking my gas up.