I have a 1987 that use to take about 15 minutes to warm up. Once warmed up engine ran great about 35mph . The other day I took the kids out to have some fun on the tube after 15 minutes engine was running mint. I ran it for about 40 minutes and the engine started running like it would when I first started it. Now the boat won't go faster then 20mph. Its starts great but wont go faster then 20mph. It seems to me like its only running on 2 cylinders. The moter is a 3 cylinder. What should I check first to trouble shoot? Has this happened to anyone else? If so what did you do to fix it. Any info would be helpful.
Thanks
Thanks