I would start by clearing all codes, then drive the car for a while and check for new codes. This way you are only dealing with current issues and not older codes that have already been fixed and not cleared. Just my.02

 

dont just go throwin parts at it. Check the vacuum line on the throttle body, if thats not the problem test the crank and cam sensors, and the check the throttle position sensor, the tps can cause this if its bad because it will not get a good reading and cause bucking but shouldnt change over hot or cold engine. my guess is the vacuum line on the intake or a vacuum line going to the evap system from the brake booster.

 

dont just go throwin parts at it. Check the vacuum line on the throttle body, if thats not the problem test the crank and cam sensors, and the check the throttle position sensor, the tps can cause this if its bad because it will not get a good reading and cause bucking but shouldnt change over hot or cold engine. my guess is the vacuum line on the intake or a vacuum line going to the evap system from the brake booster.

 

well, my next sugestion would be to remove the inspection window on the cam cover and turn the motor over by hand to find the timeing mark or marks on the cam. you have to look closely the are somewhat elusive. once you have that identified the crank marks should align with the one on the block. if not turn the engine over one more time. to do this you will have to remove both belts and remove the pulley located behind the plastic shield in the wheel well. not an easy tast but one that will identify a possable issue. if there is over 100,000 miles on the Neon it might be a good time to replace the water pump and timing belt anyways.

 

i had same problem on my 95 dohc race car that square large plug in the engine wire harness got water in it and started to turn conectors green i just soldered and shrink wraped all the wires now works great 10 wins this season and counting

 

all the sensors are fine and looks liek the vacuume is ok ive gotten suggestions that it might be a pluged cat or timing is off?

 

what did you have to do to the wires?

 

the large square plug that connects the engine harness to car harness has dirty connections witch gives false sensor readings to pcm

 

ok thanks ill check it out :]

 

it they are corroded clean them with baking soda