2002 Dodge Neon 4cyl (engine timing?)

From a dead start (0 m.p.h), i try to accellerate and i get a very quick pause and all the sudden im JOLTED forward. the slower you press on the gas pedal the longer it takes till it jolts ya, if your on a hill its possible the slower you try to initiate accelleration the engine may hiccup on you. i also have a concern when going 65-70 mph, my car feels SOUNDS like its downshifting to get a better gear to go faster but it does this constantly, maybe once every 6 seconds or something, like it doesnt want to stay in the gear its in. i have no TAC on the car to see the RPM change, but i can sure hear it… is there any correlation between the two problems???

It might be a problem with the TPS (throttle position sensor) but we need more information. Is the check engine light on? Have there been any recent repairs or modifications? Does the car drive normally in the 25-60 mph range?

The check engine light IS on, the code from the OBD II at Auto Zone says SMALL EVAP LEAK (i know its not the gas cap, maybe charcoal cannister?) As for recent repairs, I had intake and exaust valve replacement on the 3rd cylinder last summer. YES the car drives completely normal between 0-60. the RPM changing doesnt happen till im at interstate speeds of 60+, although i would say the car is a big sluggish feeling in 2nd and 3rd gears, maybe thats just the 4cyl. haha.

Changing the automatic transmission fluid would, most likely, help the shifting. As a routine maintenance item, it’s 'way past due. Check, or change, the throttle position sensor (tps). It’s job, which it seems not to be doing well, is to tell the engine computer when the throttle is moved. The engine computer, then, calls for more (or, less) fuel to match the amount of throttle movement.

Alright! THANKS! I’ll try it!

On the 1995 Neon, in the automatic transmission, there was a band adjustment which would be made when the transmission pan was removed for fluid and filter change. And, there was another transmission adjustment. If these two adjustments are still there in the 2002 Neon, now would be a good time to do them. It could help that jolting transmission gear change. Look in your MODEL and year Haynes, or Chilton’s maintenance manual.