Dying under load certainly sounds like fuel starvation. Once you get to using up all the gas in the fuel bowl it dies. Maybe dirt in the main jet, float bowl could be leaky and sunk, water in either the tank or the fuel bowl, water in the filter as mentioned. Another thing to check is your coil. it could be going bad. Once it heats up it will break it's internal connection and shut off. Then it cools enough to restart. Check your oil level. If once you get on plain the oil pressure drops, some engine systems will shut down the engine to prevent damage.
Not sure what boat and year you have.
Just thoughts.....
