My 91 Trans Am convertible with a 305 TPI engine has a slight miss/rough idle. As soon as you touch the gas and go it runs fine, only at idle does it have this concern. It runs fine at part throttle and WOT. I changed the plugs to new AC Delco, put new plug wires, new distributor cap, new rotor, and a new coil and it got better but it still has the concern. I cleaned the throttle body, this yr T/A does not have a MAF meter, its speed density. Any other ideas ? This is a daily driver and I would like it to run 100%. I have no history as I just bought it last week from the original owner, it has about 80,000 mi. Please, If any one can help me it would be greatly appreciated ! Heres the car..............

Very nice car!
Have you tried running a few tanks of injecton system cleaner through it? The grey-bodied injectors are notorious for being fussy when they get older.

TA

IAC valve and TPS. Make sure the IAC is opperating correctly and that the TPS is set where it is supposed to be. There is a manaul of how to check these somewhere on this site.

I have an almost identical car and an almost identical issue. I've cleaned and reset my IAC, but I haven't messed with the TPS. My new engine has less than 1,000 miles on it. I'm thinking my Accel injectors are the culprit. Anybody else got any input?

P.S. Just out of curiosity ... would you mind disclosing what you paid for it?

too much..........lol

Well, I think it may be the fuel pump........It died on me tonight and now it will only idle very badly and if you touch the gas it instantly dies again but will restart.

I pulled the upper intake and checked / cleaned the EGR since it had a code 32 but it was fine.

I think theres enough fuel pressure to just start the car but thats it, it runs very rough and if you spray carb cleaner in the throttle body, it smooths out a little and will rev then.

I'll check fuel press tomorrow and see if I have 44psi.