I have a 1983 pontiac firebird with a carbed 2.8. I just got it running again after 2 months. It has always had problems with idle. I tried to do it right this time and set it to 800 rpm and it will keep jumping from 1200 to 700 I don't like it like that but I could live with it. But today after driving it with it warmed up it started to go all the way to 300 bouncing up to 500 and will stay there till I give it gas then go back down. Sometimes it stalls and I have to pull over and keep cranking for a few minutes till it starts back up again. It's really embarrising. It seems to happen more when I'm in stop and go traffic but this could be just a coincedence. I checked vacume lines and they look good to me, replaced some of them anyways. Any ideas on where to start. Gotta drive to Texas on Friday so time isn't on my side. Thanks

 

Have you checked any of the choke related things? Not sure if its a cause for erratic idle but for some reason, my 84 camaro's choke plug in is very sensitive and falls out if moved slightly. If its out and i start the car, it goes and idles weirder than with it plugged in.

 

Yeah I checked the choke and all the linkage is connected so that can't be the problem. It happens when the the engine is warm too and the choke is fully open. I should also mention that I have an exhaust leak where it connects the manifold to the y pipe. Do you think that this could cause it.

 

I could very well be wrong, but the exhaust leak doesn't seem like it could be a cause of an erratic idle. Honestly I don't know, but if I come across anything that could be the reason why, I'll post it.

 

a bad pcv valve will also cause erratic idle

 

chaged the pcv valve but no luck. Any more ideas. Do you think it could be ignition related? Maybe timeing, or a weak coil? I tried to set the timeing but I can't find that wire that your supposed to disconnect. Not sure if an 83 even has that wire that your suposed to disconnect because ther is no plug in that area. Maybe it's in a different location. Anybody know?

 

Erratic idle could be a timing issue. I know when the timing was too retarded on my car, it idled funky. Started to detonate a bit when advanced too much lol. I'd check your timing for sure.