loss of power in winter weather ( snow blowing)

[stumped]

I have a MTD yardman with a courage 22 hp twin cyl motor.
When I use the snow blower it starts and runs fine for about 30 minutes, then seems to loose governor control. It won't increase power as the load increases. I can move the throttle control up and done with no response. The motor just seems to go into an idle position and stay there. The minute I move it back to the garage and wait a few minutes everything goes back to normal. I am stumped as to why it would do this

 

[SeniorCitizen]

Have you tried removing the air filter ? Check around the carburetor venturi throttle shaft area for ice that may be preventing movement.

 

[ILENGINE]

i was thinking carb icing myself