In a medium mixing bowl, mix together the barbecue sauce, apple cider vinegar, worcestershire sauce, brown sugar, garlic powder, onion powder, paprika, cayenne pepper, salt, and black pepper.

Place the boneless picnic roast into the bottom of the slow cooker.

Pour the Dr. Pepper over the picnic roast, then pour the barbecue sauce mixture over the top of the roast, ensuring it is well covered.

Once the picnic roast is cooked, remove it from the slow cooker and shred it using two forks in a mixing bowl.

Skim off as much fat as possible from the cooking liquid in the slow cooker.

Return the shredded picnic roast to the slow cooker and mix it in with the sauce. Continue to cook on LOW for another 30 minutes.