Mix flour, margarine, and pecans.
Pat into a 13x9 inch baking dish and bake 15 minutes at 375 degrees; cool.
Beat 1 cup Cool Whip, powdered sugar, and cream cheese until fluffy.
Spread evenly on nut crust.
Stir together pudding mix, lemon juice and milk; when thickened, spread over the second layer.
Spread remaining container of Cool Whip evenly over top.
Refrigerate at least 4 hours.