I grew up in North Carolina and we had one or more pig pickings yearly. This isn't the sauce my family used (takes a while to get Carolina Treat in Georgia since you have to get it mail order). I came up with my own sauce because when I take the notion for it I tend to be out of Carolina Treat. I have not found a restaurant in Georgia that has anything close to this.
In a small sauce pan that can be covered, bring the vinegar and red pepper flakes to a boil. Boil 1 minute, remove from heat, add sugar, stir to dissolve, add mustard and ketchup, stir, cover set aside to cool
Place pork roast in a crackpot, add 1/2 cup of the sauce, cook on high 6 to 8 hours, shred, and serve