Low, loppy idle then too high, then low again....
 

Hey, the GT is not doing bad, but the it's having a little problem.

1) When I first crank it after it's been sitting for overnight, it really wants to shut off if I allow it to.

2) After it has warmed up, it doesn't idle well. It'll idle high (~1100 rpm) for a few seconds, then idle low (~ 600) in a loppy kinda way (like a umh, umh umh, instead of a smooth ummmmmmh).

3) Also, if I'm driving down the road and come to a light it'll idle high like mentioned in 2), then low, then high... even when I'm driving and am slowing down for a stoplight, if I depress the clutch pedal, it idles high (above 1000) and then after I FINALLY come to a dead stop, it'll drop down, but hten go up then down , etc (as already mentioned)

Just to start off with easy things that I know haven't been recently changed anyway, I put in a new fuel filter and spark plug wires (trying to start off with the easy stuff).

Could I be losing vacuum somewhere? What is the hose that comes out from the inside of the cavern of the upper intake (directly above the lower intake)? There are 2 hoses. The smaller one on the left (if you are looking at the intake from the front of the car) seems to be old and almost corroded. From the intake, I think it goes to a plastic junction that then goes to that smog canister. It's not easy to get to that's why I haven't changed it yet.

Any ideas guys??? I don't really care for a ruff idling car........

I have a '81 Toyota truck (it's my wheeler) and I had the same problem that you have. My problem was a vacuum line totally fell off of the carb. I can't remember exactly where it was connected to, and I am at work right now, but when I get home tonight I will try to figure out exactly where it was. I don't know if this will help you other than it is a good possibility that it is a vacuum leak (hopefully). Take a piece of vacuum hose and listen through it at different places on your motor to see if you can hear anything.

Sounds like a vacuum leak to me, also could be your TPS.

did you disconnect your battery at all recently. you could just have to reset your idle. hope that helps!

I took carb cleaner and sprayed the intake and found a leak....my car does the same exactly thing. and it was the gasket between the upper and lower intake.

Thanks for your input (sorry took me so long to reply, my internet's been off and on this week).

Yes, this does seem like a vacuum problem. If it were the '79, it'd be easy to figure out, but you can never right off tell with these newer cars.... :rolleyes: I'm gonna change out that emissions hose coming from the intake cause whether that is specifically the problem or not, looks like it'll be a problem soon. I'll see what happens. If that does not do it, then we'll talk.

I have disconnected the battery recently, but this problems seems to be different than just a idle (to high or too low) problem.

Thanks.

Well, that emissions hose was the problem. I changed it out and another piece and the car runs perfectly now. It was worse than I thought it was... just about completely dry rotted. I love an easy fix. :D :D :D :)