you got no power, hesitation? check air filter, fuel pressure, fuel filter, timing, pull ox sensor and see if that helps (if so you need exhaust), throttle position sensor, throttle for goop and gunk, IAT sensor for open/closing.
fuel pumps usually dont slow down, they just stop....and most likely when you need it the most, like on the way to that new job interview or when you need to get the wife to the hospital because she's in labor....something like that.
i need more than just what you've explained. i need rpm, load % (assuming you're not talking WOT), maintenance recently done, what gas you buy (e85 or regular, addatives used...that kind of stuff.)