Preheat oven to 375 degrees, and grease some cookie sheets. Cream the shortening and sugar together. Add the eggs and vanilla, and beat until smooth and blended, then beat in the sour cream. Combine the flour, baking powder, baking soda, salt, cinnamon, cloves and allspice, then stir and toss them together. Add to the first mixture, and beat until completely mixed. Add the nuts and dates, and mix well. Drop heaping teaspoonsful of the dough about 2" apart on the prepared cookie sheets. Bake for about 12 minutes, until the cookies are delicately browned around the edges. Transfer to racks to cool completely.