elantra 5spd, 2.0 161,000, AT 135,00 new timing belt, plugs, wires, coil, cam& crank sensors, 145,000 new axles, and all 4 sturts, then at 158,000 started acting wired, new fuel filter, fuel pump sock, & pressure regulator, & still acts up? run good for days, then drive it, get up to 3,000rpm acts like the rev limiter comes on? it cuts in & out! pull over shut car off. start back up runs fine. no check engine light, buts codes come up running lean, crackshaft sensor, oxgyen sensor. acts like loose wire or connentor? can't find bad anywhere? is it bad fuelpressure? how to check? i clear codes, same ones come back, when it runs right, runs great! any ideas help please. love this car, great mpg's

 

To check fuel pressure you need a adapter that goes onto the fuel rail. Sounds like lack of fuel pressure . Probably needs a pump with that many miles but should be confirmed with pressure check. A far as those reoccurring codes I would check engine grounds. I believe there is a big ground strap on the standard trans to body.

 

I've found the fuel pump assembly on our parts page:

2005 Hyundai Elantra: Fuel Pump and Sender Module Assembly

I would concur that this is a pump issue, but could be as straight forward as the sender too.

Good luck!