Barbecued Pulled Pork Sandwiches

2 1/2 lbs pork roast
1 14-oz bottle of your favorite barbecue sauce
1 tsp brown sugar
1 Tbs fresh lemon juice
1 medium onion, chopped
8 hamburger buns or hard rolls

Place the pork roast in the slow cooker. Cover; cook on Low for 10 to 12 hours or on High for 5 to 6 hours. Remove the pork roast from the stoneware, and pull the meat into shredded pieces. Pour out any liquid in the stoneware, and combine pork with the remaining ingredients in the slow cooker. Cook on High for 2 hours. Serve the barbecue pork on hamburger buns or hard rolls.