I have a forklift with a commercial slant 6

I agree with rustycowll69 on checking to see if you have spark and fuel squirting in the carb after it dies. Could this be vapor lock happening? But only after running the engine for 10 mins doesn't sound like it is. 10 mins is a short period of time. I say fuel or spark/electrical is the issue. Again check for spark and fuel squirting in the carb after it dies. Go from there....