Season pork with salt and pepper. In a large saucepan over medium heat add the olive oil and melt the butter. Lightly sear the outside of the pork in the butter and oil. Remove the pork and add into slow cooker. Mix together Coke, chicken broth, onion, garlic, peppers, cilantro, oregano and brown sugar and pour over pork. Cook for about 4-6 hours in slow cooker or until meat falls off the bone.