i have a 350 tpi motor. ive had a problem with the car when it gets warm, it starts to run rough and almost stalls. i replace a vaccum hose, fuel injectors, plugs and wires, and a fuel pump. still nothing fixed it. i took it to a shop they ran all the tests they can think of and everything shows up normal. i drove it home today and it barley ran, every time id give it gas it would cut out and barley move. i almost didnt make it up a hill. im stumped and my mechanic has no idea....i think im gonna have to sell my car

 

i'm assuming it is an automatic with a 350 tpi. does it matter what gear it is in when it starts stalling? does it do the same thing while in nuetral or park? and when you say it gets warm. do you mean outside temp? or every time the car engine warms up? i'm assuming the latter but just want to be sure. is there ever a time that the engine seems to run well?

 

yes it is a auto 700r4. when it has stalled on me its most likey in 1st or 2nd. when i say gets warm i mean the engine. and it does run rough but less rough in nuetral. but thats because there is no load on it. the car usually runs great when i first start it up. after the engine and trans get warm then i start to notice a change. if i shut the car off when its warm, and start it up again sometimes it doesnt start or it gets real choppy and rough the idle bounces up and down and barley runs. ive checked all sensor, injector pull fuel pressure, had it on the computer everything checks out normal. nobody can figure it out, because it only happens when its warm we cant figure it out. normally the problem would be all the time so its easy to find. i checked my distributor and the wires, i disconnected them while the engine was running, all lowered the prm but cylinder #8 which means the wire, plug, or cylinder is bad. next i might have to check the manifold.

 

have you changed the #8 plug and wire? that's the easiest start point. after that it could be a couple of things. one possibility is a vacuum leak that is only showing up when the two joined materials are heated. it is not all that likely, but the easiest way to check that is to put a vacuum gauge on the intake somewhere. maybe use the brake booster line as the take off point as you will probably be best to check this the first time while it is stationary anyway. if the vacuum dies quickly after warm up then that is more than likely what is the problem and you need to start trying to isolate the location of the drop.
the other possibility is that one of the sensors is bad and is not sending the right signal to the ecu. while the engine is cold the ecu will ignore most of the sensors while it tries to warm up. it is a preprogrammed code so even if a sensor is bad it will usually work fine. once the engine gets warm, the ecu will start looking for information from sensors to control timing and fuel delivery. since you said you get it checked out i am assuming you had the ecu scanned for trouble codes. if this is the case, the sensor isnt throwing a bad code, but if one of them isn't working correctly it may be sending a signal to the ECU that is technically within range of what the computer expects as a possible signal from the sensor, but isn't really what the engine needs at that time. since timing impact is somewhat limited in the distributor driven cars i am going to assume it probably has more to do with fuel delivery than timing. the fact that the start up program usually runs a little to the rich side and seems to be working fine for start up also supports a fuel related issue. prime candidates for affecting fuel delivery are the mass air, throttle position, and o2 sensors. its kind of a long shot, but given the circumstances it may be worth investigating if the #8 wire and vacuum tests don't pan out.

 

a 1990 TPI motor doesn't have a MAF on it.
my truck had a bad cylinder and was doing the exact same thing your car is doing. I had a burned valve on the #1 cylinder and the thing was choking everywhere, and it would backfire above 3000rpm. Start with the #8 cylinder and find the problem with that FIRST. If it's something as simple as a bad plug or plug wire to the #8 then don't go spending a bunch of money trying to fix it when it's something simple. If it has no compression, figure out why. Don't ignore it when you know something is up with the #8.