I had a similar experience with my first slab of ribs on my Assassin Smoker. They were too fall off the bone after wrapping them for 2 hours. I think that the next time I will cut it back to just a hour in the foil and then a hour unwrapped. I have heard that the gravity cookers like ours do cook a little faster.
Assassin Smoker; Large BGE; Char-Broil Gasser; Black Thermapen; Looftlighter; KCBS CBJ