Mix flour, soda, cinnamon, baking powder, and salt. Combine sour cream, water, coffee, and vanilla. Cream butter, then gradually beat in sugar. Add eggs one at a time, beating well after each. Mix in chocolate. Alternately add about a third of the flour mixture then half the sour cream mixture, ending with the flour mixture.
Pour into a greased and floured 13 by 9 inch pan. Bake at 350F for 30-35 minutes until a toothpick inserted in the center comes out clean. Cool in pan for 10 minutes and then transfer to a rack. Sprinkle with confectioners sugar.