It's possible there's a restriction in the fuel tank pickup screen, or maybe the flex line from the frame to the fuel pump is collapsing, restricting the fuel flow to the pump. My 47 Mercury would stop completely after a couple of miles, and restart in 15 minutes or so. I finally found a big grasshopper lodged in the fuel line inside the tank.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!