Bought a returned Toro leaf blower today. It fires up fine and runs on choke. It will run with wide open throttle on half choke. As soon try to shut the choke off, it falls on its face and dies. I have got the plug properly and checked all the usual suspects. It's getting plenty of fuel and seems to be getting plenty of spark. I have pulled the carb and blowed through all the fuel lines. There are no removable jets, but I have blown through the ones that I can find. Any suggestions for what I should check next?