hey scotty my girlfriend has a 02 honda civic that when it takes off and in 3rd gear it gets up to 4000 rpms and then starts to hesitate and jerk. ive replaced the TPS and the fuel pump is working. what else could it be ?

No. 1-1

pressure test the pump first, low pressure does that all the time (and of course change the fuel filter first as it can be clogged.) Also pressure test the catalytic converter, clogged ones do that too