For sauce, remove any stems from peppers. Place peppers and adobo sauce in a blender container.
Cover and blend until smooth. Set aside.
Lightly coat an unheated medium saucepan with nonstick cooking spray.
Cook onion and garlic in saucepan until tender.
Stir in chipotle pepper mixture, ketchup, vinegar, molasses, and Worcestershire sauce.
Bring to boiling, and reduce heat. Simmer uncovered about 10 minutes or until sauce is slightly thickened.
Grill chicken on the rack of an uncovered grill directly over medium coals for 12-15 minutes, or until chicken is no longer pink.
(170°F), turn once halfway through cooking and brush with sauce during the last 5 minutes of grilling.