Late comer to the tread... Tim it does sound like like a bad coil. Had the same issue with my boat. It would run for an hour or so then loose power and stop. Wait 10-15 minutes and it would fire right up and run for another hour. Ran the gambit of troubleshooting for about a month.

Finally gave up and called the Island marine mechanic and explained the symptoms. He called me back about 20 minutes later and said "it's fixed". Just a bad coil as he expected. He said it is the most common cause for sudden loss of power. Boat has run great ever since.

Hope you track it down quickly!

Mike