I was bush hogging my wife's pasture and the 2N was running great for about 3/4 of an hour and suddenly the tractor started to spit and sputter. I knew I only had a gallon+ of fuel, so I assumed I had run out of gas. After adding more fuel, it would only run smooth when I pulled the choke all the way out. (note, I never had to use any choke once it started previously) It did not have enough power to run the bush hog. I then ran the tractor back to my shop, but the motor galloped when in gear. Because it had run just fine before it started to spit and puttered, I'm wondering what I should check for. I have good spark and the engine will start with only a few reveloutions, but the choke must be almost all the way out for the motor to smoothen out. Any ideas appreciated.