I was at the lake doing a test run with the '85 Glasstream that I got the day before. The motor starts easily, and Idles fine. I tried to go forward, and it dont seem like the boat is moving as fast as it is supposed to. It feels like it is barely creeping along. It has a 50hp Mariner and the boat is only 15 foot long. I dont know a thing about how to work on outboards. Any Ideas?