Place pork in the slow cooker, and fill with water until it reaches halfway up the roast.
Cook on high for 3 hours.
Drain the water and cut the pork in thirds.
Mix together salsa, Dr. Pepper, and brown sugar and pour over the pork.
Cook on low for 3 more hours.
Drain the liquid (reserving just a little bit to mix with the pork) and shred the pork. Mix the shredded pork with the reserved liquid.
Preheat oven to 400 degrees F.
Spread chips in an even layer on baking sheet.
Top with pork and shredded cheese.
Sprinkle on black beans, corn, tomato, onion and jalapeños.
Bake for 5-10 minutes or until cheese has completely melted.
Remove from oven.
Spoon sour cream into a Ziploc bag, clip the corner of the bag, and drizzle over nachos.
Top with cilantro and serve.