Sift flour, baking soda, and salt together into a bowl and set aside. Cream the butter and margarine together until fluffy.
Add sugars and combine until light and fluffy. Add eggs one at a time, scraping the bowl with a rubber spatula and then mixing after each addition. Add vanilla. Add flour mixture and mix just until blended. Scrape with the spatula. Roughly chop the pecans so you have some large and some small pieces. Add chocolate chips and pecans to the cookie mixture and fold in with the spatula.