lost power

hey guys, im new here, bought my mk3 1990 supra over the summer. recently ive noticed sometimes between 3000-3500 rpms there will be an evident lack of power, but once it gets past 3500 its continues its fast revving nature. i dont know why it would rev quickly to 3000-lull to 3500, then go back to usualy acceleration. any comments or ideas would be greatly appreciated.

n/a or turbo? manual or auto?

1990 N/A, Manual, 130,000 miles. previous owner took meticulous care of the car, all records and everything. it doesnt do it all the time, just sometimes, and im pretty positive im not imagining it because its pretty pronounced. hopefully that clarifies something.

So does it just do it under WOT (wide open throttle)? Have you tried putting the pedal down 3/4 or so and see if it's still doing the hesitation? Also when was the last time the car had a major tune up, plugs, wires, fuel filter, clean the TB, check around for obvious vac leaks, and check the engine codes while your at it. Lots of things it could be so hopefully this will narrow it down. :)

It does it from 8/10's to 10/10. Thanks for the advice, ill look into that.

Forgot to mention the O2 sensor if you haven't already thought of it.

Mine's doing something similar... It has a slight, almost unnoticable drop in power in the ranges you described, but you can still tell it's there. Get a check engine light too, but the codes didn't tell me anything. It only seems to happen when you climb to the rpm quickly. Going slowly to it seems to reduce the effect, but that's no fun!