Hello! I have a Scag 52" with a 18 HP Kohler Command. The first time I've had a problem with it was today, it died while cutting. I had to choke it to get it started and it would only stay running under full choke. I pulled the carb and found no dirt, but thoroughly cleaned and blew it out. The fuel pump is working fine also. I even pulled one off of another working mower to make sure. I know the gas is good, because I filled up all of my mower's at the same place and time. Any suggestions of what might be causing this? Thanks for any help!