Help trying to fix vapor lock run into other issues

[Dlm11]

72 c10 350 mechanical fuel pump. I’ve been fighting vapor lock for awhile. I recently installed an AC delco gf423 fuel filter with a vapor/fuel return line. To the best of my knowledge it has an orifice in the return side of the filter. Also has an under bed tank. It starts,idles, runs fine in the driveway. When I drive it I get about 1/2 mile and it starts feeling like it’s starved cutting out all but shutting off and sputtering and I barely make it home. I pull in the driveway way and it runs fine. My fist thought is is the filter running to much fuel back to the tank and the second is that the filter is 5/16 and all my fuel lines are 3/8 between that and the fact it’s returning fuel to the tank do I need to raise the level in the fuel bowls and possibly adjust the carb? Any help will be greatly appreciated.