You mean you are cranking the mower in gear? The starter motor is spinning the engine, then the transmission, then the wheels. I suggest not to do this, you will fry your battery, and starter and possibly the engine. The starter motor is very small and only meant to have the power to turn the engine over freely.

You might have a blocked carbie or jet may need replacing, Or not getting enough air look at the air cleaner, or breaking down in your eletrical system.