In a large dry skillet, toast ancho peppers on both sides until they crackle and just turn color, for about 1 minute on each side. (Be careful not to burn them; it will make your mole bitter.) Place in a small bowl; cover with boiling water and let stand for 30 minutes to re-hydrate. Drain and discard soaking water. Remove seeds from ancho peppers; set aside.
In the same large skillet cook onion and garlic in hot oil over medium heat for 5 minutes or until onion is tender. Stir in sunflower kernels, cinnamon, cumin seeds, and allspice; cook and stir for 3 to 4 minutes more or until mixture is very fragrant. Transfer mixture to a blender or food processor.
Add 1-1/2 cups of the chicken broth, the tomato, bread, ancho peppers, and chipotle peppers to the blender or food processor. Cover and blend or process until smooth, adding more chicken broth if needed.
Transfer mixture to a large saucepan. Stir in remaining broth, chocolate, and 2 teaspoons sugar. Bring mixture to boiling; reduce heat and simmer, uncovered, for 30 minutes or until mixture reaches desired consistency. Season to taste with salt, pepper, and additional sugar. Cover and keep warm.
Meanwhile, season pork tenderloins with salt and black pepper. For a charcoal grill, arrange hot coals around a drip pan. Test for medium-high heat above pan. Place meat on grill rack over pan. Cover; grill for 30 to 35 minutes or until a meat thermometer registers 155 degrees F. (For a gas grill, preheat grill. Reduce heat to medium. Adjust for indirect cooking. Grill as above.) Remove meat from grill. Cover with foil and let stand for 10 minutes. (The meat's temperature will rise 5 degrees F during standing.) Slice tenderloin into 1/2-inch thick slices.
Place tenderloin slices on a serving plant. Top with mole sauce and sprinkle with pumpkin seeds. Makes 8 to 10 servings.