Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Does it have adjustable carburetor? With it running, the high speed screw would need to be adjusted to get it to run correctly. If the carburetor is non adjustable, I would look for a new carburetor with adjustment screws,
They are to cheap to try any kind of repair. See the above link. If yours has the odd screws, you can use a piece of tubing slipped over the heads of the screws to turn them for adjustment.