We were out today doing some fishing and ran into a problem. The boat was running just fine and then we went to go hammer down on it and it reved up slowed the throttle down and putted around. It seemed like if we stayed in low gear it did just fine. When we got off of the river, went back to the house and took the prop off. Thought it could be a spun prop. But it looked just fine. On something like this can looks be decieving. It felt pretty tight on the shaft. We have no idea what it could be and was just wondering if anyone had any ideas. It seems like when we hammer down on it, it wants to rev through the roof. Is something not engaging. Please help if you can. Much appreciated.