df100 suzuki 2009 bogging

[100 suzuki]

I have a weird problem, motor runs fine up to.about four or six hours then bogs down to about 1200 rpms , I put the boat in neutral then try to put in gear, then it still does the same thing, so I put it in neutral again , shut off the motor ,restart it again then it works fine. Any ideas ? Thanks!!!

[artdf175]

I would consider starting with the fuel tank vent
eaisily plugged be spiders or other small critters
is the fuel pump bulb going flat at the same time?
that is where I would start looking