Spastic mercury 40 hp 3 cyl 2004 , runs like crap

[Scubasteve1]

Guys , I am getting really frustrated

My 40 3 cyl merc 2 stroke is driving me nuts

It has
rebuilt carbs, new float needles etc, checked for specs and clearances
new fuel pump
#1 has a new coil and spark plug wire
3 new spark plugs
new fuel filter
new fuel lines
new fuel tank and bulb ...pressure checked to see if any air leaks
Stator checked for high and low issues..none noted

I have new fuel and run seafoam

Here is the issue
It runs great for the first 5 min, then goes to limp mode,
total power reduction..5300rpm to 2500 ish...idles rough in limp mode


Last year it did this before all of the above repairs...

I am a pretty good mech but am out of ideas

Please point me in a good direction

Thanks

steve

PSI added a new water pump and fuel lines on the engine...

Checked the vent, and its clear

 

[tikki]

Just a thought.
Is the fuel enrichment solenoid stuck open? so it gets to much fuel?
clean the spark plugs and use those as a reference.