Combine flour, sugar, pumpkin pie spice, baking powder, baking soda,and salt in a bowl and set aside. Add pumpkin and oil; stir in cereal just until moistened. Add dry ingredients and stir just until combined. Fold in pecans and raisins.
Pour into a greased Bundt pan. Bake at 350 degrees for 60-65 minutes or until cake tests done. Cool in pan for 10 minutes before removing to wire rack to cool completely. Dust with powdered sugar before serving, if desired.