missing can be caused by a plug that getting dirty or a bad plugwire/connection. A wire that's chafed allowing it to short out. Like wise with the kill switch. or any wiring connection that is not good and tight. Water in the fuel will make your day. Partly plugged filter inside the tank which you all know the tank is spotlessly clean and will never do that.
Then there is the did you hear that thing as well.

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