Heat the oil in a Dutch oven or large pot over medium-high heat and brown the meat well, turning often, about 15 minutes. In a bowl combine the barbecue sauce, vinegar, broth, sugar, mustard, Worcestershire sauce, chili powder, onion, garlic and thyme. Pour over the meat and bring to a boil. Cover tightly with a lid or aluminum foil and roast in the oven for 3 to 4 hours. Remove the meat and shred it with a fork. Return the meat to the pot and keep warm.