How is the rubber line between hard line from tank to pump inlet? Had a Belvedere once, that line was old and soft, I'd stomp the throttle and pump vacuum would suck it shut.Drove me NUTS figuring that out.
You might try to disconnect the input side of your fuel filter and shoot some compressed air back through the line to the tank. Might be some garbage clogging it up.
fuel lines could be clogged with dirt and crap in ur tank or it wouldnt hurt to clean the carb
Check the float in your carburetor.
I have a 1972 Ford F 100. I have been having few issues I replaced the mechanical fuel pump along with the fuel lines and the problem remains. If I drive short distances or not very fast then I can drive fine. its when I really put my foot into it or drive very far I have the problem what happens is it starving for fuel so much so that it stutters and dies. I have a glass in line filter so I can see if there's gas getting to the front end of the motor or not, and after it dies I look under my hood and the glass fuel filter is empty. but if I leave my fuel pump on it will replenish and I can start it up again... does anybody have any ideas what is wrong? any help would be much appreciated