My 97 GMC bogs and losses power after 3000 rpm

I have a 97 GMC Sierra with 5.7 it looses power
after 3000 rpm. before 3000rpms it starts well
Idols well, it doesn't miss, has no sign of power
loss. Plugged in scanner  had a bad throttle
position sensor replace that twice 2 different ones
nothing no fix. Next I checked to see if the mass
airflow sensor was clogged cleaned it seemed to
help but then it went right back to the same
problem, changed it same problem. Did a
distributor, cap rotor spark plugs. Check for a bad
ground put a new battery in it as it  did have a bad
cell in it new alternator. Bypass the catalytic
converter. Nothing seems to help what next. I do
use this as a plow truck and it was running fine
before  I plowed and did have a little bounce of the
blade so I think something  may have been rattled
loose but nothing appears wrong.