Remove stems from ancho peppers and peel them open. Discard seeds. Place peppers in a bowl and cover with about 2 cups of boiling water. Let sit 30 minutes.
Preheat oven to 350 degrees.
Place softened peppers and 1 ½ cups of the soaking liquid in a blender. Add pumpkin, garlic, cumin, sugar, salt, and red pepper flakes. Blend until smooth.
In a medium bowl combine pulled pork, corn, sour cream, and ½ cup shredded Colby Jack cheese. If pulled pork has been refrigerated, warm it in the microwave first.
Lightly spray a baking dish with cooking spray and spread 1 cup of sauce along bottom.
Place tortillas on a microwave-safe plate, cover with a damp paper towel and heat for 20-30 seconds to make pliable.
Place about ¼ to 1/3 cup filling in a line across each tortilla, roll up, and place seam side down in the prepared dish. Cover with another 1 1/2 cups of sauce. You will have extra sauce that you can serve with the enchiladas.
Sprinkle remaining Colby Jack cheese on top, cover baking dish with aluminum foil, and bake for 30 minutes. (Spray underside of aluminum foil with cooking spray if it looks like it might touch the cheese.)
To serve, sprinkle with cilantro and queso fresco cheese if desired.