Salt and pepper the roast well. Place in the crock pot with the onions and garlic.
Pour Dr. Pepper over the roast. Cook on high 4-5 hours, or until tender enough to shred.
Remove from the crock pot and shred. Pour out most of the liquid from the crock pot so there's just a little on the bottom.
Combine ketchup, mustard, honey, Worcestershire sauce, brown sugar, and garlic powder to make the sauce. Combine with shredded pork and place back in the crock pot.
Cook on low for 45 minutes to an hour, or until completely heated through. Serve on your favorite bun or roll.