Happened to me in my Bonanza a few weeks ago. I was would you believe crossing water between Scotland and England. Managed to get myself 17 miles from the coast and 20 odd miles from the nearest airfield. It has runs smoothly for 650 hours over 6 years before that. Mixture full rich improved the situation but it was still doing it. My behind was twitching!
Took it in to have it sorted and they replaced plugs and cleaned the injectors and some other little bits and it now runs smoother than it has for four years. Must have been an underlying problem.
I had life jackets onboard but no raft. Guess what else I carry onboard now.
Strangely I have flown over water between Blackpool to Llandudno and Blackpool Scotland many many times over the years without a thought as it feels like you are near the shore but I would never make land if the big fan stopped. It has made me think a bit.
I few years ago I flew to Ireland at 2000ft with our new baby onboard. That fills me with dread since reading various ditching stories over the last few years.
I also considered my Bonanza turning into a Baron for a few days after the misfire but I have got over that for now.