^ good idea about running on a external tank next time the proplem happens. Great way to pinpoint where the problem is. If it runs fine on the external tank, look into a clogged fuel pick up, collapsed fuel line or water in fuel. if it runs bad on the external tank, check fuel pump and carb. I believe your napa filter is a water seperator, pretty sure i had the same one on an old Ski nautique i used to own. Water in the fuel can be a real pain in the gas. Might be best to remove the tank and completely drain and clean. Water is heavier than gasoline and will always settle in the bottom of the tank, where your fuel pick up is....