Whisk together all ingredients for BBQ sauce, except corn starch and water.
Place trivet in bottom of Instant Pot and add one cup of water.
Rub seasonings over chuck roast & place on top of trivet in bottom of Instant Pot.
Pour BBQ sauce over the top of the chuck roast.
Close lid and valve and set timer to Manual/Pressure Cook, high pressure for 20 minutes per pound.
Natural release the pressure (let the pressure go out on it's own until the pin drops)
Once pressure has released, open lid, remove beef and shred with 2 forks or meat claws.
Mix together 2 Tbsp cornstarch with 2 Tbsp cold water. Pour into sauce in Instant Pot.
Turn Instant Pot to Saute and let sauce simmer until it thickens, about 15 minutes.
Mix meat back in to sauce.