Transfer the ribs to a large non-reactive glass or ceramic dish pour 2 cups of Coca-Cola or Dr. Pepper over them. Reserve the third cup of the soda for a sauce to be made later. Let the ribs marinate, tightly covered with plastic wrap and refrigerated, overnight.
Pour the remaining 1 cup of soda into a blender or food processor and add the ketchup, brown sugar, chili powder, pepper, dry mustard, and cinnamon. Mix until smooth and well blended.
Put the ribs in a roasting pan that has been coated with cooking spray, brush with the sauce, and roast covered in a 225 oven for about 2½ hours until very tender. (Can be done the day before. )
To finish, grill over high heat, basting with the uncooked sauce until the outside is crispy, about 10-15 minutes. Meanwhile simmer the unused sauce for about 20 minute until a little thick.