Service Engine Light 99 Ford E150 5.4L Triton

I am looking for help. I have a P0402 Engine Code which means EGR excessive emissions recirculation flow. I had the changed the EGR Valve changed and cleaned out the lines. The light came back after 3 Weeks. I guess the next step is to change the DPFE (Differential Pressure Sensor), but I don't know where it is, and don't know if its an easy job. Any help locating it, with schematic, or suggesting a Manual would be much appreciated.



Thanks
Fred