In a small bowl, combine all the dry ingredients: brown sugar, paprika, garlic powder, onion powder, black pepper, salt, dried thyme, dried rosemary, dried oregano, and cayenne pepper until well combined, ensuring that there are no clumps.
Pat the pork roast dry with paper towels to remove any excess moisture. This will help the dry rub adhere to the meat. Generously coat the pork roast with the dry rub, massaging it into the meat to ensure even coverage.
Preheat the oven to 325°F. Place the pork roast (fat cap side up) in a large high-sided baking dish and cover with aluminum foil.
Place the pork roast in the oven and cook until the internal temperature reaches 145°F, as measured with a meat thermometer. I roast a five-pound cut of pork for around 6 hours. This makes the meat fall apart for the perfect pulled pork. If you want a more solid roast, I recommend roasting for about 20 minutes per pound, but cooking times may vary depending on the size of the roast.
Once cooked, remove the pork roast from the oven and let it rest for 10-15 minutes before slicing or shredding. This allows the juices to be redistributed, the result is a juicier and more tender final product.