help 240 wont rev high?????

well.... i got a 1989 240sx with a 93 ka24de swap i just rebuilt the motor put it all in and now it wont rev up past 4500 rpms at full throttle i have already checked all the wires replaced the 02 sensor fuel filter plugs/wires new ecu ??????? anyone got any ideas please let me know

What happens when it reaches 4500?

id check fuel delivery

If its like a rev-limiter type thing then its prolly a short in your wiring harness. I had a friend that had that happen when his front wheels decided they didnt like where his harness was.