i have recently bought an 89 firebird formula that had the original 305 tbi taken out and reused all of the parts on a 350 long block. the car runs fine going down the road, but at idle it drops to about 600 rpm and doesnt stay in one spot. it will slow down a bit, pick back up, and repeat. at idle you can also smell gas in the ehxaust. the only problem i could think of that would cause that would be bad o2 sensors. can i get confirmation on that or maybe any other ideas? thanks in advance

 

poorly adjusted Throttle position sensor. I was battling a problem like this for awhile. I changed the whole throttle body out with a replcaement that came with a tps, IAC, injectors etc. But before I did that I tried two different TPS and IAC and still had it. I think it was possibly a leaky injector seal and bad injector. But I also changed the intake gasket at the same time too. one of those things fixed it..what exactly..I dunno. Try and adjust your TPS. Thier is a thread here somewhere about it do a and you'll find it

 

ah ok. ill try it out. also, if i tap the gas at all at idle itll kill the motor. same problem?