88 chevy cuts out under load

88 Chevy Z71 350 motor 4x4. Seems to run fine at idle and also revs up fine when in park. Put in gear and try to drive it begins to cut out and bog down around 35 mph. Put it too the floor and it will rev up and go for a while then begin to cut out again. New fuel filter, New coil(a wire that comes from the coil to under the dash is unhooked and is hot when the key is on), The throttle body is delivering fuel from both sides(at idle).

Any advice is greatly appreciated.