1995 Chevrolet Silverado Chevy

I have a chevy truck with a 305 one day I was driving home from work and the truck just lost power at high speed when I would push on the gas pedal it would make a growling sound and I would not go over 45mph so I got it home and rebuilt tbi it did not fix the problem so I changed all the sensors the map sensor temp sensor throttle sensor that did not work same problems so I just put a carbureted manifold and a new carb on it and still having the exact problems I put a fuel pressure regulator with a return on it and a fuel pressure gage and its set at 7psi the engine will not run past idle with or without tbi I have no idea what's wrong