ascastil

My car is hesitating at WOT, higher rpm's worse when i get near 5000. The fuel pressure stays at about 42 WOT. The computer is programmed to run with cats on it but i dont have them on yet. Could this affect it? Also i'm getting a PO336 code, I've already swapped sensors, but it didnt fix it.I'm sure it must be the wiring and ill work on that next. Anyways the question is would that code have something to do with it? I didnt think it did cause the car started doing this before the code popped up. Oh yeah its a stock fuel pump and new fuel filter.