Koo Koo Roo was crowing on Mar. 30. The Los Angeles-based restaurant operator said Chairman Kenneth Berg would step down for health reasons and be replaced by none other than Lee Iacocca. Word of the ex-Chrysler chairman's involvement sent the stock up 72%, to 3 7/16. As acting chairman, Iacocca is said to be working with new CEO William Allen on restructuring Koo Koo Roo, which operates 38 chicken eateries and 14 Hamburger Hamlets. But Wall Street's elation faded: By Apr. 1, the stock settled at 2 29/32.