1. In a small bowl, mix chili powder, onion powder, garlic powder, salt, pepper and cayenne pepper.
2. Rub the spice mixture on all sides of the pork.
3. Cover and refrigerate for at least 2 hours, or overnight.
4. Place pork in a slow cooker.
5. Set on low heat and cook for 10-12 hours.
6. Transfer from the slow cooker to a roasting pan and shred with two forks, removing any large pieces of fat.
7. Pour the broth into a heatproof pitcher or large fat separator, and skim off fat.
8. Put the pork back into the slow cooker.
9. Combine the barbecue sauce and 3 cups of the skimmed broth.
10.Stir into the pork and cook 2 hours.
11.Using a slotted spoon, remove the pork from the slow cooker.
12.Place the meat on a serving platter or on individual buns.
13.Serve the remaining sauce alongside.
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