In a small bowl combine all the spices. Rub the pork with about 6 to 8 tablespoons of the dry mixture; reserve the rest. Wrap the pork with plastic and refrigerate overnight.
Place the pork, fat side up in a slow cooker. Add the crushed tomatoes and diced tomatoes. Cover and cook on low for 8 hours.
Remove pork and shred with two forks. Add pan juices as needed to keep pork moist.