Try replacing the fuel filter and check bowl, any screens (bottom of tank & pump inlet) etc. Siphon out or drain as much fuel as you can if not all. Refuel with new pump (known good) fuel and treat the fuel with a good quality diesel fuel additive. I mix John Deere Summers formula (JD dealer) with Howes Diesel Treat (Flying J station). Take the tractor out and try it again, if it runs good, run the tractor full load after a good warm up to push anything through the system that may have gotten past the filter water separator. Just a few thoughts. Good luck!