I have a 2004 4 stroke 60 hp fuel Injected mercury big foot on my pontoon boat that will start running rough and almost die at high rpms. Like it's starving for fuel I've checked and cleaned the fuel filter. Replaced the fuel line from the tank to the motor including the primer ball. And also checked all vents for obstructions. After I did all that it ran fine for a couple days but now it is doing the same thing again and I'm stumped. If anyone has had this problem before and or has any thoughts on what could possibly be going on that would be great thanks in advance for any help or advice you can give.