Larger cuts of pork such as shoulders and butts contain a lot of interspersed fat which needs to be rendered during the slow cooking process of barbecuing. Fat begins to render, or melt away, beginning at an internal temperature of approximately 180 degrees. It takes quite a bit of time cooking at 220 degrees for the meat to reach the internal temperature of 190 degrees. This allows time for the fat to render which also creates self-basting process. If you don't have a meat thermometer, you'll known that the meat is done when you can freely turn the bone which is situated inside of the meat.
When serving pork always serve pulled or shredded pork so as to retain all the natural juices in the meat. If you choose to slice pork, you're doing your cooking process a dishonor due to the drying nature of the sliced meat. Try both ways and you can tell the difference.