power loss under acceleration

i have a 93 S-10, 2.8 TBI 5-speed...what it does is when i take off it accelrates normal but a few seconds it like wont go any faster, pressing the pedel all the way to the floor does nothing, i have to back off the gas and change gears to pickup speed, does it really bad in first thru third gears, and it happens at low rpm, im not over reving it....i changed the O2 sencer, plugs, cap, roter, air and fuel filter, changed oil, nothing has helped. its not like its running out of gas, it feels like its straining to go when it hits that spot in the rpm.....any ideas

I would first use the diagnostic capabilities of your ECM....

Do you get a "Check Engine" light? See if your local auto parts store will download trouble codes; many do this for free. Just because the light does not come on does not mean there aren't any trouble codes logged.

I would think something that serious would set a trouble code if not turn on the Check Engine light......

check fuel pressure, egr valve, and pcv valve.

no trouble codes have been locked in as of yet and were checking the fuel pressure today...will let you no on that
thanks