Pour beef broth into the Instant Pot.
Season all sides of the roast with salt, pepper and garlic powder. Place roast in the bottom of the Instant Pot.
Add in onions, peppers, celery, and garlic on top of and all around the roast.
Pour tomato sauce, BBQ sauce, and Worcestershire sauce on top of roast. Then place bouillon cubes on top of roast with thyme and rosemary.
Place the lid on top of the Instant Pot and move the valve to SEALING. Press the PRESSURE COOK (MANUAL) button and set timer for 65 minutes (or 20-25 minutes per pound, depending on the size of your roast).
When the timer is done, let the pressure do a NATURAL RELEASE and then let the roast sit on warm for at least 1 hour (I sometimes will let it sit on warm in the Instant Pot for 3-5 hours, just to let it really get tender).
Remove roast from Instant Pot and slice into pieces (it should pretty much fall apart by this point).
Serve with mashed potatoes and gravy on the side and of course with Texas Roadhouse Rolls. :)