19' Kencraft with Suzuki 115 (2007 model year) with less than 50 hours. Was running fine until it suddenly stopped. After restarting, it will now go only about 15mph. RPM will increase to max >6000 but speed does not increase with increased RPM beyond 2000RPM. However, when trying to go in reverse, it does not engage at low RPMs. Reverse kicks in at high speed with full reverse throttle. Propeller seems to be ok. Any thoughts on what the problem is?