Evinrude Gremlin

[rcnight]

I was running in this past weekend trying to outrun the approaching storm when my 1997 Evinrude 150 went from 5k to 0 rpms in a few seconds. No fault lites and no warning of oncoming problem, ran fine all day. A passing boater was kind enough to tow us the remaining mile or so. Tried to start it on the way in with no luck. Would crank but wouldn't fire. I went out to the boat today to check for spark and it cranked right up. I did replace the kill switch recently. I checked the wiring and all good. What would cause such a rapid cut-off? Any ideas on what and where to look?