I bought a red top swap for my s13 hatch. I finnaly got it to run after multiple issues now it runs great on idle but when you go to give it a decent amount of throttle it falls on its face it breaks,up badly. I have a new walbro 255 I did a boost leak test I'm good there, New Ngk plugs, timing done with a timing light at 15 degrees, stock Sr ecu with Sr maf. I'm lost what else could be the issue anything at this point would help.

DId you replace the turbo gaskets?? I bet it's one of those inner or outer gasket... Check your FPR, PCV Valve check it to be sure it isn't clogged.....

Most of the turbo gaskets were replaced if not all of them. The Pcv valve is new but I havnt checked the fpr.

Did you replace the fuel filter as well? How about O2 sensor? What was the condition of the motor? I'm going to assume slightly abused since you said it was giving you issues running. Have you done a compression test on all the cylinders?

The motor is actually in great shape. The issues it was giving me because of the wiring on the harness I got. I got a lot of it sorted out I found out the tps was off I fixed that and it ran 100percent better. I am still getting a slight break up when you really get on the throttle but when you get into boost it gets better. The fuel filter is new as well as the 02 sensor.

If the TPS is just slightly off, it can cause break ups. Do you have a manual boost controller, EBC, or are you running stock PSI??

Sounds like it's running really rich if it smooths out once boost is applied. TPS seems to be where you need to be focused at. What does your a/f look like?