Complex sentence: Stack became a sketch writer on "Late Night with Conan O'Brien" in 1997, and served as a writer, actor and editor on the show and after O'Brien's move to "The Tonight Show" in 2009.
Split into simpler sentences: Stack became a sketch writer on "Late Night with Conan O'Brien" in 1997, and served as a writer, actor and editor on the show. Stack remained with O'Brien after O'Brien's move to "The Tonight Show" in 2009.