I have a 1994 '19 Ebbtide with a 5.7L Yamaha(basically a Chevy 350) with a Yamaha outdrive. The engine is a strong runner and I had no problems with the boat until last Saturday. I was pulling tubes around the lake all day and on the last run i ran into problems. I clutched the motor forward and idled until the slack was out of the rope and then punched it. The motor increased in RPM but the boat didn't go any faster than idle. Everything looks normal on the outside (i.e. not dragging any thing or broke the prop). I can idle around the lake all day but as soon as i apply power it feels like it slips or something. It?s like a bad clutch on a car. I know nothing about outdrives. Any help would be appreciated.