It could be a float problem, I don't want to dismiss anything yet, but I doubt it. I would be checking two other things first. One, check the electrical lead, on the fuel shut off solenoid, from the carb back. What I am looking for is a crack in the insulation or a loose connection that is short out the solenoid when the engine is tipped in one direction. Two, I would install a clear plastic fuel filter between the pump and the carb. Any small one will work for this test, because it will be removed later. What I am looking for is whether there is a change in the fuel flow during different types of mowing situations. If you see a drop in the fuel flow when tipped to the right, I would suspect a pump issue. It there is no drop in fuel flow and no bad wiring or connections, I would be rebuilding the carb again.