On an old old car with a mechanical pump, sediments in the tank can clog the intake filter "sock" and stop fuel flow while theres a suction. When enough debris accumulates, flow stops and engine dies. That takes away the suction and the debris falls to the bottom of the tank again. Then she'll start again and run until repeat. Could be something like that going on either in the tank or inside the filter now, causing the trouble. FWIW no ethanol gas used to just kinda make yellow jello in bike carb bowls but E15 or 10 seems to create moisture corrosion at the top of the gas. Attacks castings more, IMO. 2 year old E10 was no prob in my 99GT, but you can tell old gas a mile away by the smell. I whiff that odor often at work.
