Speculation mounted yesterday that ``American Idol'' judge Paula Abdul may be voted off the hit reality show after ABC airs a damning investigation tomorrow night. Abdul, who has been under fire for erratic on-air behavior, may voluntarily vacate the judge's podium after ``Primetime Live'' airs answering-machine messages she left for a 24-year-old contestant. The Drudge Report says Abdul personally coached the contestant and then tried to cover it up. Speculation surrounds Corey Clark, who was run off the show last season after it was revealed he assaulted his teenage sister. Clark is peddling a tell-all biography in which he claims...