I have a nearly new Kohler K341 replacement engine in my Simplicity tractor. After mowing for 10-20 minutes, it starts to loose power and die down. Sometimes, if I choke it, it will continue to run, however this does not always work. I have checked the fuel system and cleaned the carb out twice, blowing out all the jets. One thing I have noticed, which makes me wonder if it is getting hot, is the fact that the carb is so hot when it starts doing this that you cannot even get close to touching it. if you spray carb cleaner on the side of the carb when this happens, it boils and sizzles right off. I was just wondering if the carb could be getting so hot that it is boiling the fuel in the bowl? also, i have checked all the cooling fins and they are clean and clear. Usually, when this problem happens, I can let the mower cool off and it will be good for another 10-20 minutes. I also wanted to tell you all that I have checked the bowl after this happens (when it is cool enought to touch) and there was fuel in the bowl, so I suspect the fuel pump is working fine. any help is greatly appreciated.