I have a 2000 Four Winns with a 5.0 Volvo Penta GL engine. I just bought this bought, it has less than 94 hours on the boat. The first time I took it out it ran great at both WOT and at low throttle. Stopped a couple of times to swim. When we started back to the boat landing it slowed and shot down. Got towed in. Got home began checking it out, disconnected due line from carb. It was pumping fuel, checked the coil and the primary side was reading 11Kohms. I read that it should be around 9Kohms. Went to the local parts store and bought a high performance coil. Took the boat back out and it ran fine again for a couple of hours. Did the same thing again. Got fuel at the carb. Any ideas?