ok, I just switched my chipped p30 for a virgin p72. My original ecu was the p72 and I actually traded a friend for the p30. We traded back and now i'm kinda studdering in lower rpms. When it gets to around 4.5-5k rpms, the car is fine. you can press on the gas pedal and the motor gets louder but doesn't go anywhere, and it just studders in the lower part of the rpm range. Do you have any ideas??? If that is too confusing, then please tell me.

P.S: its a JDM B18C