I launched in the morning let warm up at the dock for 15 minutes then took off, ran for 10 minutes or so at 2500-3000 rpm then started backfiring through the carb(qjet) and surging the eventually stalling. I was able to restart, I put it in gear then died again. It wouldn't start again. I lost spark at coil. Next morning I replaced the coil and it fired up. I let it run a 3000 rpm for 15 min at the dock put it in reverse and it almost died. I go to put it in forward and it died and wouldn't restart. No spark at the coil. It is a thunderbolt 4 ignition with alpha out drive. The boat is a 1989 bayliner arriva 2150. If anybody had this happen to them or has seen this before let me know what was wrong. I thank you in advance