A Great Neck developer who was sued for deploying a fake FBI agent to intimidate an elderly Flatbush man into signing over his home has flipped a house at 259 Maple Street between Bedford and Rogers, Flatbushed has learned. Park Slope Associates picked up the PLG property for $500,000 in 2013 and sold it off last month for $1.4 million after a renovation, according to records. Roughly two weeks before that sale closed, The New York Post reported that a 66-year-old Flatbush man sued the same company for scheming to divest him of his property at 2319 Bedford Ave. between Albemarle and Tilden. According to the suit, Park Slope Associates sent