i know in my 95 accord vtec, when i did the motor swap the vtec wasnt connected, in the top end she was hurting, spitting and nnever making it to 6000 rpm, also the 2 vaccumm lines comng from the front right of the intake manifold , those can be crossed and cause a problem that your describing, check all vaccumm lines using a diagram for your car. even though a check light will be on if the vtec was not connected or defective.