Mix together spice mixture
Put pork roast into a sealable bag, and pour in soy sauce, half the can of Dr. Pepper, and half the spice rub.
Marinade in the fridge for 4-16 hours
Put roast, and marinade in slow cooker on low heat add in salsa. onion, green chilies and 1/2 a cup of brown sugar
Cook 8-10 hours
At about 7 hours, pour contents of slow cooker into a strainer, emptying the sauce it cooked in.
Shred the pork and return it to the slow cooker.
Open enchilada sauce, sriracha, the other half of the brown sugar, Dr.Pepper, and spice mixture
Cook one more hour and enjoy in tacos, burritos, enchiladas, in salads, or over rice