In a medium bowl, mix together the salt, pepper, Coke Zero, and brown sugar. Place the roast with this marinade into the crockpot or in a gallon-size bag and let it marinate overnight or for at least two hours.
Take the pork out of the fridge and add 1/4 cup water to the marinade. Cook on LOW for 4-6 hours or HIGH for 3-4 hours. The pork should be able to shred very easily with a fork.
Drain all the liquids and shred the pork using two forks.
In a medium bowl, combine the Coke Zero, green chilies, tomato sauce, chipotle peppers, garlic powder, cumin, chipotle chili powder, brown sugar, and salt and pepper to taste. Stir to mix well and add the mixture back to the slow cooker with the shredded pork. Continue cooking for an hour.
Serve with black beans, cilantro lime rice, or in tortillas!