ok....now the knock sensor?

[nekoabandoned]

motor is breaking up( just doesnt want to climb like it should) at higher rpms 4.5+ im guessing the ecu is retarded the timing for some unknown reason, im leaning towards knock sensors but its not throwing any codes which baffles me. nothing but 55 , any ideas guys ? btw this motor was just redone and yes compression is perfect.

thanks for any help in advance