A few hours before beginning the slow cooking of the ribs, make the rub by combining garlic powder, onion powder, chili powder, paprika, mustard, and salt in a bowl and mixing well. Rub the mix into the meat and let sit for at least an hour. The mixture will begin to cure the meat.
About 30 minutes before beginning to barbecue, heat the grill.
Wrap ribs in heavy duty aluminum foil and place on the grill over indirect heat and slowly cook for about 2 hours, turning occasionally.
While the ribs are cooking, begin the sauce on the stovetop. Combine apple juice, tomato juice, molasses, Worcestershire sauce, hot sauce and barbecue sauce in a saucepan, stirring to mix well. Simmer over low heat until it beings to thicken. Let simmer for 1/2 hour. Reserve about 1 cup to serve on the side with the ribs, and use the rest to brush on the ribs as they barbecue.
When the meat begins to become fork tender, unwrap ribs and begin brushing on the sauce. Continue to apply the sauce to the ribs during the barbeque process. When ribs are able to pull apart, they are ready.