Pontiac Repair: 95 sunfire misfire at constant speed, ac delco, vacuum line

Question
I have 95 sunfire 2.2 ,auto with 165K. The problem is the car jerks or misfires to maintain a constant speed. It's more evident on lower speeds but it is felt on higher speeds also.Under acceleration and idle the car is fine. I have recently changed plugs and wires and the problem still persists.
please help

Answer
Hi Tony:

Were the parts relaced chasing this problem or did it crop up after the parts were replaced? I suggest using only AC Delco plugs and wires. You could have an issue with an EGR valve on this car as well usually when they go bad it's more of a surge then a misfire. The spring in the valve goes bad and the valve opens more then it should and cause a lean "misfire" try unplugging the vacuum line to the valve Plug the vacuum port with a screw and drive it. My guess is that will fix it. If so replace the vlave with a Genuine GM replacement part. No aftermarket fits all valve. I would also suggest replacing the Fuel filter as well. Good luck