I have a 2000 ford explorer, the check engine light is on, the codes are P0442 and evap control system leak detected ( small leak), P1507 idle air control underspeed error and P0401 EGR flow insufficient detected, what should I be looking for to fix this problem, I need to get this vehicle inspected and emmission tested my 3/1/09

As a certified tech a can say with all certanty that you need a DPFE sensor

DPFE sensor will probably help; you may still need the idle air control motor, as these typically go bad on Fords. The EVAP leak might be a bad gas cap; check the seal to see if it looks compressed.