I'm not sure if this is a new problem or not. I have had the truck for a couple of years, but just barely started doing some extensive towing with it. It primarly only does it towing, right after towing, or when I really get on the gas.

It has the Edelbrock 750 1407 carb.

My gas vents might be plugged or not existent. The other day I went to fill up and when I took the cap off one of the tanks there was a lot of pressure built up.

It doesn't sit for very long. Sometimes it will sit for a week or two (as we try to use the wife's more fuel efficient vehicle most of the time-that 460 is a thirsty beast).

I might just try to change those pick up screens.

 

If it is those screens, do just have so much sediment after 35 years that changing them might not even help?