The reason this is urgent is because I came up to Iowa from Georgia to get my 1991 Z28 305tpi, and drive it back south. But its having some problems. In mid december i took it out after sitting for a month or so to change the oil so id be ready for the drive. After filling it up with gas and driving it about 5 miles it began idleing rough. I changed the oil, it looked fine. Now I just got here in Des Moines and cranked her up. She has no power, still ideling rough and is now backfiring from the exhaust. I drove the old gas out and filled it up. No change. I really need some sugestions on what to try. I have to get back to sign up for school early next week. One other thing, a few months ago it was kicking O2 sensor codes, could it have anything to do with that?

Here's the first thing I would do. Pull every plug wire to make sure there are no cracks in them. This has happened to me 3 times until I bought some Looms, wire separators, and heat sleeving (taking no chances). The car would idle like crap, lost power, and would backfire. IF that checks out ok, I would check to make sure the cat isn't clogged.

Ill check that. I dont have a cat.

Shecky,

I don't supose you have a fuel pressure gauge with you? (You might guess where this is going.)

What error codes were you getting a few months ago?

I DO have an fuel pressure gauge in my trunk. And i have a adjustable fuel pressure regulator installed. Though, vadar, i dont know where you were going with your response. The codes that were kicking dealt with the 02 sensor. I cant remember what it was exactly. Another thing about my problem is that when its cold, just after i cranked it, it idels okay.

Symptoms are along the lines of my car. Vader, greaseape, and zroc are all helping me tackle the problem. Heres the link:
https://www.thirdgen.org/techbb2/sho...4&goto=newpost
Do you have emissions tests where ur at? Just wondering if your car would pass in its current state. Also, hows your fuel economy? Ive had my eye on this thread also: https://www.thirdgen.org/techbb2/sho...4&goto=newpost
Again, simular symptoms.

one thing, plant protection, most of the problem the guy had in the first post you refered me to delt with maf system, im pretty sure the '91 tpi has speed densety. 2nd, there are no emission checks were i am from.
as far a gas millage goes, i really have checked it since it started acting up. i drove it on a 1000 mile trip in september and i got about 24 mpg. honestly, the poor z28 is pretty embarassing to drive right now with terible idleing, sluggish take off and backfiring.
ill be working on it on tuesday and will keep you guys posted on my progress. thanks for the suggestions so far and would appriciate some more.

Well I replaced the cap and rotor and the O2 sensor, and I run like, well, a honda. Now lets hope the '91 Z will make it from Des Moines, IA to Macon, GA. My fingers are crossed

Where I was going was the possibility of low fuel pressure. Depending on your DTCs, you may be lean. Were you getting a '44' earlier? Or was it a general signal loss code, '13'? Since the ECM basically ignores the O² at cold startup (until the timer expires and the O² is generating voltage) you might idle O.K. when cold, but get "goofy" as soon as the ECM hits closed loop.

Just a guess at this point, but knowing the fuel pressure would eliminate a lot of possibilites or get you pointed in the right direction.