Why does my truck bogg down or flood out when giving it too much gas?

92 gmc sierra 350 boggs down or floods out after driving it
for a few minutes. Once it starts, u can shift to neutral while
still rolling down the road, switch truck off and then crank it
back up, put it back in drive and it'll run smooth on all 8. U
could stomp it and it runs like a champ for bout a minute
and then its back to bogging down when u climb a hill or
simply press gas pedal a lil. Changed fuel pump and filter,
then pit/cock blew out and had to replace radiator.
Changed distributer cap, rotor button, coil pack, map
sensor and cooling sensor. I need help!