Heavy duty rockers Ratt and Vixen bring the house down during this special presentation of ""MTV Unplugged."" Taped in high-definition TV at the historic Ed Sullivan Theatre in Manhattan, Vixen, who were joined by Cinderella guitarist Fred Coury, performed ""Love Is A Killer"" and ""Edge Of A Broken Heart."" Ratt, in an unusual performance, covered Fleetwood Mac's ""Oh Well"" and Creedence Clearwater Revival's ""Born On The Bayou."" ""MTV Unplugged"" with Ratt and Vixen, with high-definition imaging by Captain of America, marks the airing of a third high-definition program on the network. An excerpt from the MTV Unplugged Book...""Another subtext of Unplugged is to see who's really got the goods. In many ways, the show was a reaction to the slick, lip-synching mentality of the 80's: we were fighting the good fight against the Milli Vanillis of the world. Not that either Ratt or Vixen were lip-synchers. Hardly. It's just that their brand of metal. Set List: Love Is a Killer [Vixen] Edge of a