my 1990 TII has power cuts around 6krpm has mild streetport, 14lbs stock turbo, and 3" exhaust.
Bad tune?, fuel pump?, im not sure but i just bought it and was wondering

 

STOP DRIVING THE CAR!

Get the boost down below 12 PSI.

More details are needed. Stock ECU?

 

I hope the fuel system is upgraded, as well as the ECU. Clarify what you mean by "tuned". If you have a standalone or any sort of programmable ECU, you could very well have a serious lean spot up top due to tuning. The stock turbo isn't going to hold that 14 psi at 6k RPM (especially not w/ a streetport), but around 10 psi may be possible still. Hopefully you have something better than a stock TII fuel pump, since increased boost pressures mean increased fuel pressure, and the stock pump has little flow at pressures above stock.

 

by tuned i mean not tuned. i bought the car from a guy i know and was just wondering.
im getting a plug n play and will be getting a fuel pump here soon. right now i dont drive it im still driving my mustang. appreciate all the help