I recently purchased a 1963 Starcraft with a 35 hp Super Seahorse. The owner says that it has sit the last two years, but ran great when he parked it. I went to work and changed plugs, fuel and a new fuel line with primer bulb. I shot carb cleaner in the carb and put sea foam in the new fuel. It ran great in a barrel of water in forward and reverse and accelerated. However, I got to the lake and when I go forward, it will not go any faster than trolling speed. When you give it throttle it dies every time. I can put it in reverse and it accelerates fine. It seems to have trouble pushing the boat forward. Not quite sure if it's a fuel problem or lower unit. I am thinking it needs a carb kit. Any ideas? Thanks