Preheat oven to 250°. In a large bowl, combine cereals, pretzels and pecans. , In a small microwave-safe dish, combine maple syrup and butter. Cover and microwave on high 45 seconds or until butter is melted. Stir in vanilla. Pour over cereal mixture and toss to coat., Transfer to a 15x10x1-in. baking pan coated with cooking spray. Bake 45 minutes, stirring every 15 minutes. Cool on a wire rack. Store in an airtight container.