Originally Posted by 85Dave
if the snow is too thick and heavy it will stress the motor some and slow it down, I know mine does this every now and then as well.
If you are good with motors I suggest taking it apart and giving it a good cleaning. My first thought is the gears are stressing the overall motor and could need some repair or oil. I also suggest looking into the carb. and cleaning it out real well. If it has a float and bowl setup the older floats can start leaking and wont float as well which would start stalling the engine after a few minutes of use and would also give problems on startup.
Its best to let the engine warm up for about a minute before going to work with it as well. This puts less stress on the parts which will keep the motor in shape.