Trim excess fat from roast. Cut roast in half or thirds to fit in crockpot. Place meat in plastic bag in deep dish.
Stir together tomato juice, vinegar, garlic, Worcestershire sauce, salt, sugar, basil, thyme and pepper. Pour over meat and close bag. Marinate overnight in refrigerator, turning twice.
In crockpot, place onions and carrots. Place roast on vegetable. Add marinade, cover, and cook on low heat for 8-10 hours.
Remove roast and vegetables. Skim off fat from cooking liquid. Measure two cups cooking liquid into saucepan. Return meat and vegetables to crockpot - cover to keep warm.
Blend 1/2 cup water slowly into 1/4 cup flour; stir until mixture is thickened and bubbly.
Place meat on a warm platter and top with vegetables. Pour some gravy over entree, pass remaining gravy. 6 servings.
