Misfiring all of a Sudden

You burned a exhaust valve with our new gas from Russia. Did you know their lowest octane over there is 92 and their mid grade is 95. And no ethanol added. Our government is screwing our engines up intentionally. Forcing the extermination of the combustion engines. All I can tell you all is run your engine on the rich side or dig its grave. Klotz leaded octane boost 2 bottles per tank.