I have an '02 5.0 L Mercruiser engine, carb. Not EFI. It will start right up when engine is cold but after running for awhile it will crank, almost seem to start, spit or kinda backfire but won't quite crank. Had to get Sea Towed last outing....OUCH!! My guess is the ignition coil is going bad, works cold but not when hot or maybe the sensor in the Thunderbolt V distributor. You thoughts or suggestions are greatly appreciated! Kevin