Does this thing rattle no matter whose gas is in it? It is not unheard of that regular gets dumped in the premium tank either by accident or design. If you always gas up at the same place, go somewhere else preferably a brand name station.
Make sure it isn't still sucking oil thru the intake. I would hold off on the thick gaskets because the loss of quench will likely hurt more than help. We're missing something here because there are lots of guys here running similar combos without having to resort to race gas.
