Hey I've got a 98 Cavalier LS with about 127,000 miles on it. Bought it used over the summer and never had any problems with it aside from minor electrical issues Over the past month or two I've had a problem that's been getting progressively worse. When accelerating or going up a larger hill the car starts to shake or jerk rapidly until I give it enough gas to get through it. Most of the time when it starts I will give it more gas and the engine won't respond right away as if it is mis-firing. The car also stalled a few times lately when backing out of a parking spot or something. The check engine light is not coming on so I cannot plug the car in to find a problem number to research it further. I can only assume the cause of this is a mis-fire although I'm not really one to diagnose it. When the shaking starts I can usually look at the RPM guage to find it shaking rapidly by abot 500 rpm's. I don't really have a clue where to start looking to correct this problem and any help or insight would be appreciated.

 

if you are sitting still in park or neutral does it act up when u rev up
might be a bad spot in the tps

or could be the iac idle air control since you siad it happened when u backed out once

 

Not so much when I rev it up, but when I first start the car it shakes around a bit and I can watch the RPM guage shake up and down. It seems to be a lot worse at higher speeds and when I get to around 60 ish it's harder to accelerate without the engine mis-firing, giving me very little power to get going. A friend mentioned that maybe it's the EGR valve but I'm not really sure....