1996 Sentra hesitation at 45-60 mph

On a 96 Sentra 4 cylinder, it starts hesitatiog and bogging out starting at 45mph and continues to do it up to 60 mph. The brake light come on for a few seconds when this happens, then goes out. Why it is the brake light and not the check engine light is beyond me. Anyway, a scanner was put on it and it has P0170 for fuel trim. Any ideas on where to start or what to look at? thanks.

that code usually points to one or more of the following:
exhaust/intake air leak
o2 sensor wiring fault
faulty fuel pump
faulty injector wiring
leaking injector
damaged or poor connection of ECM harness connector

start with the air filter, sounds like your car is gasping for air, and also the reason for setting the code, too lean a mixture

P.S. The car may be a little shaky during all of this which is probably why the brake light is coming on, try pushing in the button on the brake handle and see if it will go down any further.