Robert Siegel talks to songwriter Mike Stoller of the team Leiber and Stoller about the deaths of two doo-wop performers. Bill Mitchell of the Clovers died last week at age 71. Billy Guy of the Coasters died Tuesday at age 66. Stoller and his partner wrote many of the best known songs for both groups and knew the men. The Coasters' Searchin and the Clovers' Love Potion Number 9 were among the songs written by Stoller.