I wonder if that crap Sam's Club gas that started this whole mess affected it somehow?

I'll do all that you suggest. For the time being, I put the 80 yr old Packard gas cap on the truck. No plastic or rubber to get messed up. Just a simple vented cap

1950 Chevrolet 3100 (Ol' Roy)

1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)