Hey,
Lately I have been noticing a loss of horsepower in the neon and today when I tried to rev it up a bit in 2nd gear as well as third gear it would go up however at around 5 1/2 thousand rpm's the car would buck a little and pretty much refuse to go past though I didnt want to push it and break the engine. I am overdue for an oil change which I am doing in a minute however is there any other reason you can think of this would happen? all fluid levels are fine and the spark plugs are new and gapped properly. Thanks.
~Christopher

mine did the same thing and i changed the ecu but i have like 10 of them so its easy for me to change out so try that if u can get to one or try from another neon.

Air flow restriction can cause that easy.

PCV valve, air filter and so on. Check the small stuff first.

Plug wires.

Old wires on new plugs is a common cause of spark leakage down the sides of the spark plugs to ground instead of through the electrodes to the air-fuel mixture. (This is why the factory recommends replacing both the plugs and the wires at the same time.)

Sadly, if the porcelain has been etched by the spark, you'll need another new set of spark plugs, too.

Jim