Diesel mechanic help with lawnmower sounding like it’s starving for fuel when in a bind.

Will change fuel filter and hydraulic filter this afternoon to see if that works but stumped on what else to do. It’s hydrostatic so could it also be hydraulic issue when turning blades on and trying to turn? It’s a reel mower and when I try to turn its sounding like it’s dying down. When I put blades on and try to go forward it dies down. Not sure if it’s fuel or hydraulic. Yanmar engine. TIA