PREHEAT OVEN TO 300*F. IN A MEDIUM BOWL COMBINE FLOUR, SODA, SALT, AND OATS. MIX WELL AND SET ASIDE. IN A LARGE BOWL BLEND SUGARS WITH AN ELECTRIC MIXER AT MEDIUM SPEED. ADD BUTTER AND MIX TO FORM A GRAINY PASTE. SCRAPE DOWN SIDES OF BOWL, THEN ADD EGGS AND VANILLA. BEAT AT MEDIUM SPEED UNTIL LIGHT AND FLUFFY. ADD THE FLOUR MIXTURE, PECANS AND CHOCOLATE CHIPS AND BLEND AT LOW SPEED JUST UNTIL COMBINED. DROP DOUGH BY ROUNDED TABLESPOONS ONTO UNGREASED COOKIE SHEETS, 1 1/2 INCHES APART. BAKE FOR 20-22 MINUTES. IMMEDIATELY TRANSFER COOKIES TO A COOL, FLAT SURFACE.