car looses power at 4,000rpm as if it looses fuel maybe
 

I have a87 turbo supra 5 speed and at 4,000 rpm the engine dies down and i loose all boost. could that be a fuel pump or something else?

U Have A Boost Leak So Check All Pipes And Hoses Or U Are Hitting Boost Cut What Mods Do U Have

I don't think its a boost leak, when we drove it it would hit 7psi and then loose power like it was hitting fuel cut, or it was starving for fuel.

Its all stock.

Check All Fuel Lines And Pump Might Be Dirty And Check Injectors