In a large saucepan, saute the chicken, onion, celery, carrots and garlic in butter and oil for 5 minutes. Stir in the basil, oregano and pepper until blended. , Set aside 1 cup broth. Gradually add remaining broth to the pan. Stir in tomatoes. Bring to a boil. Reduce heat; cover and simmer for 45-60 minutes., Return to a boil; stir in the pasta. Reduce heat; simmer, uncovered, for 10-13 minutes or until pasta is almost tender. Combine flour and reserved broth until smooth. Stir into pan. Bring to a boil; cook and stir for 2 minutes or until thickened.