ok so i bought a gsr a few weeks ago..it has 130k its a 99, it has a b20 bottom end and an intake......when i got it my cousin suggested for me to get a p28 instead of the ecu i have now. so i can run it hard and stuff but whenever ive been doing it for a couple minutes it doesnt go past 5000 rpms it just studders and i hav to shift into a higher gear. ne one have an idea about the problem?think its the ecu?

thanks