I had the 401 and 402 codes, you can check out my results here:

http://www.contour.org/forums/ultimatebb.php?ubb=get_topic;f=3;t=006477

To make a long story short, i replaced just about every part in my EGR system (3 total) and they finall went away. I'm pretty sure the EGR valve or DPFE swap where the ones that fixed it.

1996 Contour SE Red V6 MTX

1995 Contour LX Champaign V6 ATX (my wife's beater)
SuperChip | KKM Intake | Ford Motorsport 9mm Wires | Bosch +4's | Mobil 1 | No Resonator | Knauberized Doors | JSP Custom Wing | Re-wired Fogs | Red Painted Calipers | 98+ Sail Panels | Vuncannon Alarm | Lighted Moonroof Switch | Pioneer Head-unit | Pioneer 6x8's