2020 Tohatsu MFS25 running on 2 cyl

[Mechmagcn]

Hi all!
This motor is run daily during cooler weather and on rainy days since our home is by boat access only.
It's only been used a few times this summer. A few weeks ago I thought I ran out of gas in one tank, so I switched tanks and made it home. Motor was acting like it was starved for gas, almost reach plane and then drop to one cylinder, barely above idle speed. Changed the water separator filter, dumped it out and found little water in it. No change in the way it ran. Talked to the selling dealer and he suggested spark plugs. Changed them and it would run on 2 cylinders and not starve out. Took it in for service because it's under warranty. Dealer says the fuel system was full of water and trash. Uhh....neither separator filter or fuel screen on the motor had water when I checked.
Paid the bill and put it back in the water, still only running on 2 cylinders, won't even get close to plane. Sounds like it hits on all 3 at idle, but over that only 2.
Any ideas? I've got a call in to the dealer, but they were closed by the time I got it back in the water.

 

[Mechmagcn]

This is the boat, but before the new Tahotsu.

 

[pvanv]

Verify whether you have spark on all 3. Also verify injector pressure. Pull a suspected misfiring plug and inspect it. If bone dry, no fuel.

 

[Mechmagcn]

Took it back to the dealer, they say nothing is wrong with the motor. Uhh....it would push the boat 24mph one day and won't push it over 15 now, something is wrong. Sounds like I'm going to have to try to figure it out myself without voiding the warranty.

 

[Mechmagcn]

Verify whether you have spark on all 3. Also verify injector pressure. Pull a suspected misfiring plug and inspect it. If bone dry, no fuel.

All three original plugs were identical in color. Dealer tech says the fuel pressure is 42#. They also said I have a total of 55.3 hours on it.
Going out of town for a few days, so won't pick the boat up till next week. I'll be sure to troubleshoot and find the problem before we start using it daily as the weather cools.

 

[pvanv]

If there was crud in the fuel, you could have an issue with an injector, but that's rare. If all plugs looked good, the one injector could be an issue. Pressure sounds good.