I am hoping I can get some help from anyone here who has experienced this problem. I have a Kohler 20hp (older engine). When I got the mower it ran fine until I unloaded it off my trailer. Since then I have replaced the fuel pump, all fuel hoses/filter, carb gaskets, spark plugs, air cleaner, Oil/Filter, and other items not related to the engine. Its a pain in the arse to start up unless I use a little bit of starting fluid or fuel splashed in the carb. Then it runs fine and strong. After about 15 minutes it will die and not restart. I know the problem in that the pulse vacuum line gets clogged up with Oil. I will drain the oil from the line and then it starts right up unless its been sitting for a few days then I have to use started fluid. I know that the Oil is not overfilled since the dipstick shows up oil at the bottom where the safe zone is. What could be causing this? Thanks in advance.