Sift flour. Add baking powder and salt to flour and stir to blend. Melt shortening, cool slightly. Add sugar, peanut butter, eggs and vanilla to shortening. Stir together thoroughly. Add blended dry ingredients, pecans, and chocolate chips into shortening mixture. Mix well. Spread batter into greased 13X9X2 inch pan. Bake at 350 ° for 25-30 minutes. Cool in pan on rack. Cut into bars.