Season pork with salt, pepper and garlic powder and place in the crock pot. Add 6 oz of coke and 1/4 cup of brown sugar. Marinate refrigerated for a few hours or overnight turning meat at least once while marinating.
Remove crock from refrigerator, add water, and cook on high for about 3-4 hours (or until it shreds easily). Remove pork from crock pot and discard any liquid left in the pot. Shred pork with two forks.
Step two- In the crock pot, combine 8 oz coke, green chilies, tomato sauce, chipotle chile, garlic powder, cumin, chipotle chili powder and remaining brown sugar.
Put shredded pork back in the crock pot and combine with sauce. Adjust salt and pepper to taste, cover and cook on high 1-1/2 hours more.