92 Lumina Stalling

Hello

My Lumina has recently been acting up. At a stoplight, when you get on the gas the car will stall for a second then pick right back up. When I say stall I mean it's as if I just lifted my foot off the gas pedal and then mashed it. It seems to want to do it when its gotten good and warm. It drives really well in the morning and night, but in the hotter part of the day it seems to get worse. Recently it has started jerking when just going down the road. It only does it when I am putting a small amount of pressure on the accelerator. You can not make it stall when in park, or when holding the break down and throttling. Only when in gear and going. It also does it in reverse.

So far I've replaced the Fuel Filter, it had great fuel pressure, I hadn't changed the filter in about 5 years.

Ignition Wires today.

I put spark plugs in it about a year ago, but I bought some today and am going to replace them tommorrow.

I would like to get codes off this but don't know how. The check engine light is not on.

Anyone have any ideas. Thanks for your consideration!

check the vacuum hose junction at the top of the throttle body(3 or 4 plastic hoses in rubber mount)Make sure there are no vacuum leaks.Carefull they are easy to break especially if they are old.Im assuming its a 3.1

take a peice of wire insert one end top right corner of your diagnose plug located above gas pedal, and other end next to it. count first set of lights then a pause count second set of lights

transmission Torque convertor clutch engangement.
The TCC solenoid will cause this. The TCC will not apply when you let off the throttle. It will apply again when the throttle is moved off idle. The TCC solenoid has been known to come on and kill the engine. this normally happens when the engine is warm as you described.

I would suspect a bad TPS(throttle position sensor) or iac (idle air control) valve, as the problem only happens when the car is warmed up. A tcc normally won't cause a part throttle blip at low speeds, it will cause a stall as you slow down due to the converter not unlocking as you need to downshift. Check a haynes or chiltons manual on how to pull the codes, and use the chart in the book to decipher them. My money is on the IAC valve or a TPS, but the egr is a possiblity also.

transmission Torque convertor clutch engangement.
The TCC solenoid will cause this. The TCC will not apply when you let off the throttle. It will apply again when the throttle is moved off idle. The TCC solenoid has been known to come on and kill the engine. this normally happens when the engine is warm as you described.

I could see it making the engine "lay down" on acceleration if the TCC engaged during run-up, but I've never seen that happen. Seems like something would have to be mistakenly commanding lockup for that to happen. They weren't saying the motor dies, if I read correctly, just flattens out and won't pull for a few seconds.

I do remember a TSB about the TCC appliying under acceleration and causing a condition they called "Trailerhitching" on some of the first years of GM's last RWD cars (Caprice, Roadmaster,etc.), is that what you are referring to?

Well, we've replaced, ignition coils, checked the ignition control module, replaced the computer, replaced the cam shaft sensor.

The other day it gave me a engine light for the first time, this was after the computer swap, it always takes awhile to reprogram after unhooking the battery, so I let it set for awhile idling and it came on. We checked the codes and got 35 which is idle air control. My dad unhooked it and it still did the same thing.

To reiterate the car runs like a champ, until it gets hot, usually about 5 ten minutes of driving. Then when applying the gas it will rev up, then completely throttle down, then rev right back up. Other then this the car is running really well, it has more power then it has had in a long time after all the replacements we've been doing. It only has 147,000, I drove my 90 3.1 for 200,000.

The thing is I am starting to get sick of this thing, and am thinking about a new car. maybe something from australia?

My dad is now thinking it could be a fuel injector.

Oddly i started having the same problems after i changes the plugs and wires. I would start the car it would rev to 2000 then it was go down and stall. If it didn't do that i would start the car, the revs would keep jumping, i would drive it around the block, then at a full stop it would stall. The only way to avoid that was by reving high while driving/ continuously press gas even when i don't need to. pretty safe huh? so what i did was go to canadian tire/ a machanic store, and bought some wynns additive ($4 CAD), some white can that say's renews your car or so. and it worked...i don't know how but it worked, im assuming the crankshaft had something to do with it. i drove for like 20 mins after putting that shit in, and it started rev'ing more normally.. it doesn't have a bad start(2000rpm) and when it idles my car doesn't more like a mofo no more.anyways im fuckn hungry... good luck

UPDATE:

In July I found out the biggest problem with the car, the fuel pump was bad. It couldn't deliever enough fuel under a load. REplaced the pump and the car stopped stalling.

BUT
it has never regained it's idle circuit. IT was idling like it was crazy. I took the IAC valve out and found it was broken and chattering like a bird. Took apart the throttle body and cleaned it out real well, wasn't really dirty though. bought a new IAC valve.

NOW
the car requires the throttle held in to start, and won't idle until it's been driven for about ten minutes. After that it usually idles pretty well, but sometimes just completly looses it. It occasionally flashes a engine light which reads as a Idle Circuit short. I figured it was the computer so I bought one at a salvage yard. Installed it and the car ran horrible so I figure its the wrong model or PROM. I really don't want to blow any more money on this thing. ANd a new computer/PRom would be like 120 bucks.