my vtec is hittin in at 3000rpm but its set at 4500rpm and the car keeps on bloggin or jerking back at low and highspeeds need to know whats wrong cause i sure dont when im going like 30 the tach keeps on jumping back n forth and the car loses some power i have to let go and pump the gas again and its okae for a short period then it does it again also does the same at around 60-70mph i switched ecu's in it and used my friends then it started to do that then i switched it back to the ecu that came with the car and its still doing it is it that i fuked up the ecu or is there somethign else wrong need help

 

could be vaccum leak or fuel system.