The very second it stops running, look at your fuel filter bowl....or pull the line off coming from the tank and see if you have a dribble of fuel, or full flow If it's only partially full, (or low flow from the tank if you pulled the line) you have a tank obstruction blocking most of the fuel, but allowing enough to run out to refill the bowl, and allow the tractor to start again in a few minutes.
The obstruction can be algae growth, or a bug floating around over the tank outlet, or something like that. Either remove and flush the tank, or use an inspection camera to look down in it for the obstruction.