might just have a bad IAC out of the box. i just got done having the same issue with a fuel pump i bought. would do everything but pump fuel lol

Ugh well I am back. my old lasted a lil while then it started chugging and stalling on starting but would eventually smooth out if I gave it gas. I grabbed the new one and it wouldn't work at all (engine made no difference when unplugging) so now I am getting scared thinking there is some electric voltage issue then it starts working. but ofc surging badly I come to stop sign rpm dips low then raise up or rpm dipping after a small rev. I did all the possibly reset brain drain ac on while in gear everything everyone said to do i did it to set idle. I'm gonna buy a OE from rockauto most of these new iacs suck.