I got the ski this year used. I noticed it missed at little at first when started and running at slow speeds. First time out she was fine and I rode her for 2 hours. Next time out after an hour she started missing and died. the problem got worse and finally it would barely run and kept dying. 3rd time out I encounter the same problem. After an hour of running good, the ski starts missing a little, then a lot and won't run. I find if I let her sit for an hour she'll run fine again for 30 mins then it starts dying again. I've replaced the plugs but I'm thinking it might be a coil or spark plug wire problem. Maybe something is getting hot and causing the misfire. Anybody have an idea what could be causing the problem??