Good to know I'm not alone, apparently this is a common symptom with Kohlers.. aside from those caused by bad fuel & filters. I have a 6 month old Kohler Pro CV492S 18hp and it starts and runs fine for 30-45 minutes then begins to stall like it's has fuel starvation or out of gas. Wait a while and it will run again which makes it sound like a temperature related electrical problem. The carb fuel bowl solenoid shuts off fuel flow to the carb when the key is off and prevents dieseling too.. might also be tripped by a safety tip over sensor to kill the engine. I read on other forums that the solenoid can become corroded by water in the bowl and cause trouble but I found a repair tech had already disabled the solenoid by cutting off center pin on mine.. For another shot to find a cure I used a can of dust off to chill the ignition module on the chance it was hot (even though it was cool to touch, apparently some designs get warm enough to require a heatsink). One forum suggested the fuel line was getting hot and causing the fuel to vaporize but I don't think it's the problem here. I have good fuel flow from the tank to the bowl with a new 60 micron filter & new gas. Guess I'll keep reading.. the thing farts when I shut it off too.