Frank C

I have a 2001 Caviler 2.2 that jerks when I try to maintain any speed above 30. If I give it gas or let off the gas it runs fine. I have changed the plugs - wires and coil packs, changed the oil and filter. I don't get any codes what so ever. I set the cruise at 75 mph and it jerked trying to maintain speed, going upgrades and down grads it runs smooth. The cruise shut itself off once and then I got a trac off light and the car ran like a champ, the jerking stopped and was able to maintain speed while the trac off light was on " trac off was the only light that came on" no service light no ABS light. I went home and got my OBD2 and hooked it up and started the car and the trac off was gone and I was back to the jerking while trying to maintain speed. The car idles smooth at about 750 in park. I'm scratching my head on this. Any help would be greatly appreciated!