In a sauce pan add the chicken broth, tomato sauce, chili powder, garlic powder, cumin, salt and sugar. Use a whisk to mix everything together. Heat to a boil for about 3 minutes. Whisk often to dissolve spices. Whisk often to get a smooth sauce. While sauce is on simmer, about 5 minutes or so, in a small bowl add 5 tablespoons water with 5 tablespoons flour. Whisk vigorously to avoid lumps. Very slowly pour flour sauce into enchilada sauce whisking fast to avoid lumps. Whisk while boiling about 3 minutes. Turn off heat. Sauce is ready to use.