My Case 444 (Kohler K321) seems to have a case of vapor lock. It will start fine, run great for an hr or 2 but then starves for gas, putts out and after 30-45 minutes it starts and runs fine. I tried adding insulation over fuel line that runs close to exhaust. Bad design Case. Reason I say it's that is I hear what sounds like water boiling, though TBH it's hard to hear much over the metal creaking, popping from it being hot too. Is this just an issue when in 100 deg weather? All shrouds are cleaned out as a mouse had a nest in there a few years ago but I cleaned that out. Fan works no blades missing. I can only think that it may be running lean and causing it to overheat. Help plz.