1. In a large bowl, mix together pecans, oats, sugar, cinnamon, salt, and apple pie spice.
2. Cut off a thin layer from the top of each apple. Core each apple and stuff with filling, pressing down firmly to pack it in. Top the apples with additional mixture.
3. Place the apples (standing upright) in a prepared slow cooker.
4. Place one tablespoon of margarine on top of each apple.
5. Pour apple juice and rum around the apples.
6. Place cinnamon sticks and cloves into the liquid. Cook on low for two hours.
7. Serve drizzled with caramel sauce, with a scoop of ice cream if desired.