What can cause my car to jerk?

[marvelednet]

hello. I am the owner of a 1987 Chevrolet Cavalier RS Stationwagon. It has a 2.0L I4 OHV TBI Unit engine auto 3spd. I have done nothing to the engine like mods and stuff. I have had to replace the coils. Well this is the problem with the car. When driving around 25-35mph it seems fine when you have the gas pedal depresed. When you let off the gas and the car idles back down (still going about 30mph) the car starts to jerk back and forth. I talk to one of my friends and he told me that it was a problem with the TPS. So I checked and replaced that. I have replaced the fuel injector. I have checked the gap on the spark plugs and those are fine. The Spark plug cables are new too. I have been trying to figure out what the problem is and I have had no luck. Could it be the transmission? (The engine and trans. have not been rebuilt) or could it be the AIC (I think its Air Intake Sensor or controler.. I donno).

[shlynsai]

have you tried changing the air, & fuel filter? also, the trans fluid?

[FieroSpeeder]

it could be a bad torque lockup solenoid.

its usually a common problem with gms auto trans.

[blackpanther]

have you checked for vacuum leaks or loose drive train parts (i.e. drive shaft , rear end ) ? may want to check fuel filter , fuel pressure regulator , as well as fuel pump .

[justen]

sounds like a tranny thing, maybe torque converter is going bad.