Preheat oven to 350 degrees. In large bowl mix together the cake and pudding mixes, sour cream, oil, eggs and coffee. Stir in the chocolate chips and pour batter into well greased bundt pan. Bake for 45 minutes or until toothpick comes out clean. Cool cake for 1/2 hour in pan than invert onto serving plate. Dust with powdered sugar if desired.