CBS' recent Ed Sullivan special did so well in the ratings (No. 1 for the week of Feb. 11) that producer Andrew Solt has decided to bring back the variety king in a repackaged weekly half-hour syndicated series. ''I've produced about 75 hours of TV specials in my career,'' says Solt, ''but I've never had a bigger hit than the Sullivan retrospective. It really touched a nerve with people.'' Last year Solt purchased 1,000 hours of The Ed Sullivan Show (which ran from 1948 to 1971), and he has been combing through them ever since. ''The Byrds, Lovin' Spoonful, the Doors there's just so much history in those old shows,'' he says. ''Sullivan couldn't act, couldn't sing, couldn't dance he could barely introduce guests. But he was able to attract a remarkable range of talent.'' Solt will produce another two-hour Sullivan special for CBS to run within the next year. His 30-minute Sullivan reruns (the original shows were 60 minutes each) should be ready for broadcast in 1992.