Stir the broth, peanut butter, soy sauce, lime juice, brown sugar, garlic, cayenne pepper and ginger in a shallow, nonmetallic dish or gallon-size resealable plastic bag.  Remove and reserve 1 1/2 cups broth mixture (you'll be marinating the chicken in what's left in the dish).  Add the chicken to the remaining broth mixture and turn to coat.  Cover the dish or seal the bag and refrigerate for 1 to 4 hours.Remove the chicken from the marinade.  Discard the marinade.Lightly oil the grill rack and heat the grill to medium.  Grill the chicken for 15 minutes or until cooked through, turning the chicken over once halfway through the grilling time.Heat the reserved broth mixture in a 1-quart saucepan.  Cook and stir over medium heat for 5 minutes or until the mixture is thickened.  Serve the sauce with the chicken.  Sprinkle with the cilantro.