Won't rev more than 3000 while drifting
 

Hi All

I have a 2005 American spec 350z with no VDC. I am preparing it as a drifting car but this problem has stumped my mechanics. In second gear while drifting or doing a donut, the car has a loss of power as though something is stopping it from reving above 3000. The car revs fine in a straight line and seems like it has all it's power.

Here is the setup that's relevant

New walbro fuel pump and new fuel filter
Welded differential
K&N air filter (tried with and without it)
Abs clip near brake cylinder unclipped (tried with and without)
tried unhooking and rehooking the battery
Mechanic also removed some sensor or wire where the pedals are .. still the same..

I've read a lot online but haven't found anything definitive so I appreciate any help!

In 1st too but haven't tried 3rd because haven't reached high enough speeds .. thanks

The car doesnt have TCS (Im assuming because there is no TCS button, please correct me if Im wrong and if so how to disable it)

YES for aftermarket tail lights ... but this happens when the lights are off, although yes, before the "donut" or drifting session I would have pressed breaks before accelerating, but not during.

It doesnt "redline" at 3, it just peaks at 3 to 4k RPM when drifting and then feels as though it cuts the power which gradually starts coming down even though my foot is to the floor on the accelerator. before and after this, on a straight line, it drives normally.