Cook first 3 ingredients in a small saucepan over low heat, stirring often, 5 minutes or until pepper jelly melts. Remove from heat, and let mixture cool completely.
Pour 3/4 cup pepper jelly mixture into a large zip-top plastic freezer bag, reserving remaining mixture; add chicken, turning to coat. Seal and let stand at room temperature 30 minutes, turning chicken occasionally.
Remove chicken from marinade, discarding marinade. Sprinkle evenly with salt and pepper.
Grill, covered with grill lid, over medium-high heat (350° to 400°) 4 minutes on each side or until done. Serve with remaining pepper jelly mixture.