Roro it sounds like you are running lean. My guess is that something on the engine is not sealed tight. I would suspect the back plate. The carb may also have come loose or slipped in the neck of the front housing. Check all the bolts and check the carb to be sure it is tight and sealed. Also double check the muffler. It may be partially blocked or loose. These are the things I would look at first.

Mark Shuman