I've recently got codes P0171 and P0174 which suggests my truck is running lean. The first thing I checked is for unsealed vacuum lines into the intake manifold because I thought I was hearing suction. I finally narrowed it down to something that appears broken. With the engine running, I covered the hole with my finger and my truck instantly started idling more smoothly. See the pics below.
What the heck is this and how do I fix it? Please excuse typos as I am posting from my iPhone
Btw...this is from an '08 escalade ext. sorry for multiple posts.