1. In a mixing bowl combine onion powder, garlic powder, salt and pepper well.
2. Coat both sides of the ribs well with powder mixture.
3. Preheat oven to 325 degrees.
4. Place aluminum foil on the bottom and up the sides of a large metal baking pan.
5. Lay a large baking rack inside the baking dish.
6. Place ribs on baking rack in a single layer.
7. Mix together lemon juice, barbecue sauce, ketchup and vinegar in a large bowl.
8. Pour half the mixture over the top of the ribs.
9. Cover the ribs with aluminum foil.
10. Bake 2 to 2 Ż hours or until ribs are fork tender.
11. Remove ribs from oven.
12. Turn oven temperature to broil.
13. Remove aluminum foil from top of ribs.
14. Char ribs under broiler for about 2 minutes.
15. Serve with sauce.