Another thought, I am new here and don't know your experience level with offsets, but you did say it was your first ribs on the Lang so I am guessing at least this one is new.
My Lang 84 has enough airflow to run at over 500* if you build a big fire and leave the vents all open. This is way more flow than you need to smoke at 225 to 325. I always leave the chimney vent open and I open all four intakes on startup, but once it gets within 30-40* of my target I shut down both intake vents near the body. With a smaller fire built closer to the door, I will usually run with .75 to 1.5 worth of vents open. That gives plenty of air to keep the small fire burning clean and has the benefit of slowing down the air flow so there is more contact time, less fuel burned, and less drying of the meat. I am not sure how much that will impact the amount of smoke flavor, but it is something to try.