Could be the gas you bought, and or the additive… How often are you adding additives to the fuel tank and or engine oil??
This was discussed in the thread above and possibly one or two other threads…
Still unanswered questions from the above thread…
Either you (or shop) are installing the wrong spark plugs, which I covered in prior post, or counterfeit and or non dealer parts, or you possibly have an electrical issue…
Maybe your buying cheap gas???
Might be time to find an automotive electrical specialty shop…