My 89 gta starts and idles fine till you give it some gas, then it gets 'pissed' and idles down at 500rpm, when you give it gas it stumbles, ive tried Throttle position sensor, ignition control module, and ecm. after i messed with the egr valve it runs a little better (pretty sure i need a new egr valve.), and now the SES does show up and from what i got off it ( not too sure if i read it right but..) it showed code 13 "o2 sensor or tps, which i tried tps. Could this be the o2 sensor?

Opinions?