Late to the game here, but you're doing fine. Boneless shoulder cuts are compromised muscle, which needs to pass through the danger-zone temps of 40-140* in 4 hours...you've exceeded the recommendation, being over 140* (155) in 3.5 hours instead of 4.
If you're pulling this, you may need to run it up to 200* internal, but for slicing, 190* should give a tender slice.
Be sure to wrap in foil/towels and rest for at least 2 hours before slicing or pulling...this will allow the meat to slowly cool and redistribute the natural juices in the meat (helps retain finished product's moisture content).
Smoke on!
Eric
