My Honda is a 2007. I replace the carburetor with a new OEM unit. It seemed to run OK out of the box for a few hours, then started running rough and then would not run at idle at all. It will run if I feather the throttle, but still backfires some while running. Letting off the throttle causes the engine to immediately die. I have adjusted the idle screw, but it has absolutely no effect. I am suspecting there may be some debris in the carb internally, but wanted to get more opinions before removing and cleaning it. Any suggestions will be greatly appreciated.