Place the lime juice, sour orange juice, garlic, oregano, cumin, vinegar, pepper and salt in a blender. Pulse until liquefied.
Place the pork roast inside a 6 quart or larger crock pot.
You can cut the pork shoulder into pieces if you need to.
Pour the marinade over the pork.
Cover and refrigerate at least 8 hours, overnight is best.
Remove the crock pot from the fridge and turn on low.
Add the 2 cans diced tomatoes and salt and pepper.
Cook on low for 12 hours. Remove the meat from the crock pot and place on a large cookie sheet.
Reserving the liquid to make the sauce.
Let meat rest about 20 minutes.
To shred pull the pork apart with 2 forks, discarding any fat or bones.