Remove the pork shoulder from the refrigerator 30-45 minutes before you want to put it on the pellet smoker.
Set your Traeger to 225°F and preheat with the lid closed for 15 minutes.
Place your seasoned pork shoulder fat side up directly on the grill grates and cook for approximately 3 hours with the lid closed.
Spray the pork shoulder every 45 minutes with your apple juice and vinegar mixture.
Insert a meat thermometer into the center of the pork shoulder. When the internal temperature reads 160°F, remove the shoulder from the Traeger and transfer it to a deep pan or disposable aluminum tray. Cover with aluminum foil.
Return the covered pork shoulder to the Traeger and cook with the lid closed until it reaches an internal temperature of 204F. This may take an additional 4 hours*.
After the roast reaches an internal temperature of 204F, remove it and let it rest for 30 minutes up to an hour.
When you are ready to shred the pork shoulder, transfer the pork to a large cutting board. Pour the liquid fro the aluminum tray into a fat separator and set aside.
Shred the pork shoulder with gloved hands or with two large forks. Pour 1 cup of reserved liquid from the fat separator over the shredded pulled pork.
Add sauce if desired and serve.