2001 jerks between 45 and 55mphs

[Big_Mc]

Sorry to bring this topic back up but I have a 2000 Impala LS with the 3800 and I'm having the same problem. Did you ever find a solution?

In my case, the car lunges back and forth when the car is under load. It happens at different speeds from 20 to 70 mph but it always happens when the car is under at least a slight load. When it happens, I have the gas pedal at a constant position and the tach jumps up and down from 2k to 2.5k. It will continue to do this until I let off the gas or press down further on the gas pedal. I just noticed that if I have the car in Park and press down on the throttle, everything seems fine until it reaches about 4k on the tach, then the exhaust starts spitting off and on like the throttle is cutting in and out.

At this point I have done anything to the car. This has been happening for the past year. I had the Chevy dealer look at it and the first time they replaced a solenoid on the transmission with no change. The second time, they were supposed to rebuild the tranny. That seemed to work for a month or two then it started again. Now it's as bad as ever.

Any ideas? Thanks!!