Small Engines (Lawn Mowers, etc.): Kohler Engine runs rough when hot, fuel caps, valve clearances

Question
I have a Kolher CV490s engine (on a Husq tractor) that seems to of lost power although it still starts fine. What is strange that when it gets hot it no longer likes to run at the detent (very rough, tries to stall). If I run it with a little less power I can keep it going but turning corners or going downhill while cause it to start to die (almost like you were flooding it for a second).  

Should I be looking at the carb or do you think there is a far more serious problem here ?  I have BTW checked all electrical connections that were obvious and do not see anything.

Answer
I would start with a carb cleaning.  Use compressed air from an air compressor and blow air through all the carb orifices.

I would also replace the spark plugs and check the valve clearances.

Did you download the service manual from Kohler's website?

How old is the mower?  Does the engine have a fuel pump?  Is the fuel tank venting properly?  I have had bad fuel caps but it's pretty rare.  You can usually check by leaving the fuel cap a little loose when the fuel level is less than 1/2 full...you don't want fuel splashing out of the fuel tank or debris/dirt getting in the fuel tank.

Eric