1984 Chevy C-20 350 400 Trans

[scfirefighter3]

Ok, here goes. I have a '84 C20 with a 350. It has about 2000 miles on the motor which was rebuilt by a local engine builder. Around 500 miles ago it started reading high volts (18V), and it burnt the fusible link on the fire wall up which shut the truck down. I replaced it and it ran great after that. The issue is, once the engine gets hot it bogs down and barley runs. I replaced the edlebrock 1406 with a reman. quadrajet, all fuel lines replaced, fuel pump, fuel filter, distributor, altenator, checked grounds and added extras, starter replaced, checked all wires to make sure none are pinched. The truck runs great and is very strong for the first 15 to 20 miles, and then acts like it is starving for fuel. I added a clear filter to make sure it is getting fuel and it is full when this happens. The truck only has 55,000 original miles on it, and there is no rust on the metal lines. It is to the point where I can't drive it, and don't know what else it could be. When It acts like it is starving for fuel if I feather the gas I can keep it running, then drive for around 1/4 mile before it starts again. The volts still read 16 to 18V, I frequently burn bulbs out throughout the truck, and it is running warm around 210. Before all of this it ran around 190. Thanks.