didn't get any replies in racing so I'll try here

I have a 98 2.2 cavy for dirt track.
I have a problem with the engine surging RPM's.kinda like a rev limiter, and even at lower RPM's

idle is fine, but if I rev the engine in neutral, it will kinda die(lose RPM'S ) then rev again.
holding at consistent rpm's 5k 3.5k even at 2k. it surges.

could this be fuel filter, or pump.

I don't the the money to throw at it , so I want to be one the right track before I spent anything.


thanks!