Place the pork in your slow cooker and pour in 8 oz of root beer and 1/4 cup of water. Season the pork with garlic salt and pepper, then cover and let cook on LOW for 6 hours.
After 6 hours remove pork and shred with two forks. Drain any liquid from the crock pot and return pulled pork to the crock pot.
Combine the remaining root beer, 1 1/4 cup enchilada sauce, green chiles and brown sugar in a blender and blend until smooth. Pour over shredded pork and stir to combine. Cover and cook on LOW for an additional 2 hours.
Serve tacos with warm tortillas and all the toppings. Enjoy!