my boat has been sitting for about three years. We have recently cleaned the carbs out because it wouldn't stay running. The other day we took it out and it still wouldn't stay running. It started up relatively easy. The boat use to run about 35 miles per hour but when we gave it full throttle it wouldn't get up above 26 miles per hour. Then the engine would just die and the boat would coast to a stop.<br />What can i do to fix this problem.