Hello Folks: I've got a Tiger Cub that when mowing heavy grass, engine rpm's start going up and down, will eventually stall the engine if the deck isn't cut off. When deck is disengaged, engine still runs with surging rpm's and eventually smooth out. Any Suggestions.
Also check fuel flow from the fuel tank into the carb. Less that a full fuel lone stream of fuel needs to be repaired. If you are not getting enough fuel into the carb to replace what is being using under load it will also cause the problems that you are seeing.