I have a mercury 15hp kicker and had the same issue I changed every fuel line the baulb the motor connector new filters and had the carb rebuilt twice and new thermostat was still stalling. Took a year but found out that it was gettig too hot and the gas was vaporizing so I cut out a section of the cowling on the carb side and put a vent in. It runs like brand new haven't had a issue since.