Pre-heat oven to 325oF.
Rub roast with salt and pepper.
Heat vegetable oil in a large pot.
Brown roast on all sides.
Add water, ketchup, Worcestershire, vinegar, brown sugar, mustard powder and cayenne pepper, mix together until blended.
Bring to a boil, reduce heat, cover and let simmer for 3+ hours, until tender and falls apart easily.
Pull pork apart with a fork and mix into sauce.
Serve on buns.