Peel and devein shrimp, leaving tails intact. Set aside. Drain pineapple, reserving 1/4 cup juice set aside. Combine reserved juice, Italian dressing, tomato sauce, brown sugar and mustard. Place shrimp in a shallow dish; add juice mixture, and toss gently. Cover and marinade in refrigerator at least 3 hours. Stir occasionally. Remove shrimp from marinade. Place marinade in small saucepan, bring to boil. Reduce heat and simmer 5 minutes.
Alternate shrimp, pineapple chunks, peppers, and onions on 4 metal skewers. Coat grill rack with cooking spray, place on grill over medium hot coals. Place kabobs on rack and cook 3 to 4 minutes on each side until done, basting frequently with reserved marinade. Serve over cooked rice.
