OK I need some help. I have a 25 hosre 1970 Johnson outboard. I was having problems with it planing out so I cleaned the card on it. That all went well. So I took it out to the lake to see how it ran. It started great ran just fine but when I was going across the lake it felt like the motor was hitting a log on the bottem of the lake. It did that about 3 times and then kicked out of gear. The only way it will stay in gear now is at idle speed. It will work fine in reverse but not in forward. Does anyone have any clues?