Combine the flour with salt; coat chicken thoroughly. Brown chicken pieces on all sides in hot oil; drain. Transfer to a crockpot. Stir together the lemonade concentrate, brown sugar, catsup, and vinegar; pour over chicken. Cover; cook on high heat setting for 3 to 4 hours (Or set on low for 6 to 8 hrs.) Remove chicken; pour cooking liquid into saucepan. Return chicken to cooker; cover to keep warm. Skim fat from reserved liquid. Blend cold water slowly into cornstarch; stir into hot liquid. Cook and stir till thickened and bubbly. Serve chicken with gravy over hot cooked rice.