Partially tough pulled pork after 12 hours
Always try to avoid spiking the temp. It's good to monitor and adjust, but consistency in temp is the most important thing with that method. Much like braising, meat reaches a point of no return where it starts to expel moisture during slow cooking, and that may very well be due to cranking it up.

Next time, just cover the meat and allow it to cook until it's time to rest, and allow it to rest covered for an additional 30 minutes if you had difficulties with even cooking. It's actually better to go a little lower and a little longer than crank up the heat.