In a large bowl, stir together vinegar, water, oil, brown sugar, salt, red pepper flakes and cayenne pepper until salt is dissolved. Remove 1 cup marinade; set aside. Add remaining sauce to ribs. Seal bag and marinate for 4-6 hours in the refrigerator. Remove ribs from marinade; discard marinade.
Prepare grill for medium-high heat. Grill ribs over indirect heat for 50-60 minutes or until pork is tender and the internal temperature reaches 160-degrees. Baste ribs twice with reserved marinade during last 15 minutes of grilling.