I took it out this morning for a wake up run and it ran fine for about 15 minutes. Then it started spitting and sputtering. I pulled the hood and we cruised easy back to the dock. loaded up and came home. i checked comppression and it was 115 on both cylinders, pulled the plugs and nothing wet didnt apper to be fouled. It will start and idle fine but when you wot it spits and sputters but will go full throttle. Any suggestions to start troubleshooting?