car. 97 nissan maxima(problems go on with both 95/97 ecu)
have an 05 3.5 with 3.0 timing. timing was looked over about 6 times. i have a 3.0 tb on spacer that was mad so tbs is the same as factory and not moved or touched

car bucks and hesitates under light throttle. but it don't do it all the time. maybe every other red light then next 2 red lights in a row then not at all for a wile then happens a lot. I've had the issue for a wile now. everything on the car worked great swapped the motor with zero codes. now I'm getting a p0300(sometimes i clear the light and don't come back right away) a p0150 witch is the rear cat 02 sensor. thats because i have a 97 02 sensor and have not changed it since i plugged in the 97 ecu. I've played and messed with bunch of things to see what it can be. I've searched many threads that all go to nothing and don't tell the problem. only thing i came up with is maybe fuel pump is beat. its a brand new one i put in after having issues with pump after the swap first started, so i was thinking about swapping that out. need help with it. if i can't get it soon I'm going to pull the 3.5 put old 3.0 in and sell the car and the motor.

i love driving it nothin can beat it. any idea guys