Do you have a way to safely gravity feed fuel directly to the carb from another source? Maybe another small fuel tank or bottle? Obviously am looking to see if the issue goes away when the carb is fed from an alternative source. If the problem is still there you can forget the fuel lines being the issue. If the problem goes away you can forget about replacing the carb. Now you can look at the fuel lines or anything else that might affect fuel delivery. There is an issue that was very common with this engine but it's something that normally happens from day one and not something that develops over time but I wouldn't rule anything out. The issue from brand new was the oil drain back holes in the head were too small and oil couldn't drain back properly into the crankcase. Those drain back holes also let pulses from the crankcase work the fuel pump. When the oil blocks those holes the fuel pump stops working. If this is the issue you should have had this problem from day one but the symptoms you describe are very similar. The rocker cover would have to come off on the fuel pump side to check those holes. Kohler even has a service bulletin on drilling out the holes that were too small. I believe they suggest a 1/4" drill bit but we found that sometimes wasn't enough so we would suggest a 5/16" bit and that did the trick.
