Place pork roast in the crock of a slow cooker, and add 4 cups water. Cook on High for 5 hours.
Remove pork from the slow cooker and drain liquid. Cut the pork into 4 pieces, and set aside. Puree salsa in blender. Combine the pureed salsa, cola, brown sugar, fajita seasoning, taco seasoning, and green chilies in the crock of the slow cooker. Add the pork, and cook on High for an additional 3 hours.
