I am fairly new to the smoking game, but have done a whole bunch of ribs, butts, shoulders, etc. & getting better all the time. Until now............. Put on a bone in shoulder (6lbs?) @ 225*. (I have a separate temp guage instead of the factory one) I maybe spiked to 250* a couple times due to my crappy Chargriller w/side burner. But for the most part it was 225-235* for just about 5hrs. Smoked for 2.5hrs on the grates, then placed into a foil pan with plenty of juices, brown sugar, etc and covered with foil, just as I have done a bunch of times. I had an electronic probe in it as usual and after less than 5hrs the internal meat temp rocketed to 212-216* depending on where I checked it. Took it off right away and brought it inside. The meat was tough as h$ll, would not pull apart, and there were actually small bits right near the bone that were still red. How could internal temp be so high, so quick and yet the meat was tough as nails. The taste was just fine, great smoke ring, juicy, etc. Right now, it is in a slow cooker to try and soften it up. WTF happened? Could the problem be because it was a shoulder instead of a butt?