Combine tomatoes with juice and broth in slow cooker. Sprinkle flour evenly over bottom of small skillet. Cook over high heat without stirring 3 to 4 minutes or until flour begins to brown. Reduce heat to medium; stir flour about 4 minutes. Stir in oil until smooth. Carefully whisk flour mixture into slow cooker.
Add sausage, onion, bell pepper, celery, carrot, oregano, thyme, and red pepper. Stir well. Cover; cook on LOW 4 1/2 hours to 5 hours.