Suddenly sluggish 40 hp Johnson VRO

[woodieturner]

I have a 40 hp Johnson VRO. It runs like a scalded ape... normally. Today I had it out and after a couple stops I started up and came in. I hit full throttle and after a minute someone hit the brakes. All of the sudden, it just dropped to about half power. No sputtering or jumping, just lost power.
I checked several things that I knew how. The throttle linkage is ok. The fuel line is clear. Fuel pump is not issue. Fuel filter is clear. Spark plugs look ok, but not too sure how to test those.
The question is what could make this suddenly sluggish? I've read posts about compression and carb cleaning, but would think that something like that would be more gradual, not running awesome for months then in a minute running sluggish

 

[175se]

Re: Suddenly sluggish 40 hp Johnson VRO

compressi0n check is what you want do--dirty card can cause big problems--example: dirty carb=no fuel to cyl. cyl leans melts piston. really happens that fast.