From Ford CD Manual,
DTC P0402: CHECK FOR EGR FLOW AT IDLE WITH EGR VACUUM HOSE DISCONNECTED
Diagnostic Trouble Code (DTC) P0402 indicates that Self-Test has detected EGR flow at idle.
NOTE:
If DTC P1405 is in Continuous Memory, diagnose that first starting with �«HE50�».
Possible causes:
-- EGR valve stuck open.
-- EGR vacuum regulator (EGR V.R.) solenoid vent plugged or iced.
-- EVR circuit shorted to GND.
-- EVR circuit shorted to VREF.
-- Pinched/iced pressure hoses.
-- Improper vacuum hose connection.
-- Plugged/pinched EGR V.R. vacuum hose.
-- Plugged EGR tube.
-- Damaged EGR V.R. solenoid.
-- Damaged Differential Pressure Feedback EGR (D.P.F. EGR) sensor.
-- Damaged PCM.
In the past threads, most P0402 codes have been due to a faulty DPFE sensor.
Originally posted by chongo:
Did someone call me out.......LOL
here you go. 
Also read this.
http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/1b/ca/1e/0900823d801bca1e.jsp
