Chop your 3 lb pork shoulder into 3 equally sized pieces. You can leave the string casing on the pork. Pat dry with paper towel (this will get you a better sear)
Combine all seasonings and spices in a small bowl and rub all sides of pork with the mixture.
Turn on the Saute Function of your Instant Pot and once the LED reads "HOT" add 2 tablespoons of oil and sear all three pieces of pork on all sides until brown. Remove and set aside.
While Instant Pot is still on Saute function, add 1/4 cup water or 1/4 cup root beer to the pot and deglaze the pan by using a flat wooden spoon to scrape all the seared flavor bits from the bottom of the pot.
Place the steam rack (comes with IP) into the pot and return your pulled pork to the pot. Add in your root beer.
Secure the lid of the Instant Pot, set your vent to "sealing" and using Manual Function set timer to 40 minutes
After timer is complete, allow the pork to Natural Pressure Release for 10-15 minutes. After that, CAREFULLY turn the vent to "vent" to release any remaining pressure.
Remove pork at let sit 5 minutes before shredding with 2 forks. Enjoy on tacos, sandwiches or in casseroles or soups.