Kohler Engine Loses Power Under Load

[Kubicek]

I have a mower with a Kohler engine that loses power under load. I've brought it to the dealership, but they can't seem to find the problem. Help?

 

[Wildlife]

Is the head gasket leaking?

 

[Pharmaboi]

Would maybe help to know what the dealer did try, as it could be a number if things!
Fuel filter restricted?
Dirt in the carburetor fuel jet?
Air intake leak?
Or if it's running rich and smoking it's the air filter.
Or maybe they were trying to tell you that you gotta slow down!