Mine did that two summers ago. I pulled the right cover, checked the ignitor wire gap, it was fine. Put it back together with a new gasket and it's been fine ever since. They updated the gap spec from what is in the book, I can't recall the new one, but it's in the tech vault. The gasket is an SOB to get all the old gasket removed. I did it without pulling the from the internals of the engine and just laid it on a milk crate for scraping, took about an hour!
