IRVINE, Calif. -- A 6% drop in same-store sales at Taco Bell restaurants has prompted executives of the fast-food chain to make several key changes, including the ouster of the ad agency that created the immensely popular chihuahua mascot, whose utterance, "Yo quiero Taco Bell," became a national phenomenon in 1998. The operator also announced it was replacing Peter C. Waller, president since 1997, with Emil Brolick, a 12-year veteran of the Wendy's fast-food chain. Though sent to the pound, officials said, the dog may make cameo appearances in future commercials.
