In a medium Saucepan over medium-high heat, make a gastrique by bringing the dark brown sugar, molasses, white vinegar and Worcestershire sauce to a gentle boil.
Once at a gentle boil, remove from the heat and add the mustard, garlic powder, onion powder, cayenne, black pepper and paprika powder. Let sit for 15 minutes.
Stir in the ketchup and return to the stove, and simmer over low for 30 minutes.
Remove from the heat and add the basic bbq rub.
Let cool and then refrigerate for up to 1 month.