Someone brought a 9.8hp to me to repair. They complained that the engine would bog down as they tried to accelerate. They also noticed fuel leaking from the carburetor. I checked the compression and spark: both were good. I removed and cleaned up the carburetor. When priming, fuel squirts from the carburetor's main port when the bowl is full. Inspection of the float and needle valve reveal nothing unusual. I can only start the engine with full choke and with the throttle position at start. After the engine is idling, reducing the choke causes the engine to rev. up excessively. Reducing the choke and throttle together prevents the excessive rpm but the engine will die as the process continues. Any ideas about what the problem is?