I have a 1991 bravo BBC thunderbolt iv ignition. Two trips ago the boat had a hard time getting on plain had a big miss under load I put a tune up and fuel filter on it. It is better but still has a slight miss/hesitation under load and a 200-300 rpm surge when at a cruse. Any thoughts I know the ignition pickup and module could cause this prob buy not putting the right timing for the heavy load and could cause the rpm surge under cruse. thanx

Providing you changed the plugs, cap, rotor and wires during your tune-up, I would next go to the carb. Maybe the module, but my bet is the carb. Same exact thing happened on one of the motors in my Sea Ray.