2010 Mercury 60 - Loss of power at high speed

I have a 2010 Mercury 60 that will stall after running at high rpm (~ 5,500). It's as if it has run out of fuel. I throttle back and in most instances it doesn't actually cut off. After I sit for 30 seconds or so idling I can accelerate and will run fine for another 1-2 minutes and will do it again. If I press the primer bulb it'll actually pick back up and run for a few seconds. I connected an external fuel tank,line, & bulb and it did the same thing so that tells me it's not in the boat fuel tank, line, fuel/water separator but under the hood. I've replaced the mechanical fuel pump. Also, it has new fuel filters.

Any help would be great.

Any luck resolving this? Cheers

If the gas tank vent is restricted it will slow or even stop the fuel going to the engine. Try loosening the gas cap to where it no longer seals and run it and see if there is a difference.

No luck solving this issue yet. As for the gas tank vent, I don't think this is the issue since it did the exact same thing with an external (portable) tank, fuel line and bulb. It has to be something under the hood of the motor.

Are there any fuel hoses on the engine that haven't been replaced? It actually sounds like the fuel pump but since you've already looked at that I'm not sure. I've been fooled by electrical issues that looked for all the world like a fuel problem so try having someone keep the bulb pumped up to make absolutely sure that it's fuel, after that we are due for some serious head scratching.

Looking at this again I thought of something, what if the problem is in the fuel connection at the engine? We never think about that being able to go bad or be restricted, try bypassing that connection for a test and see what happens.