Air filter housing cover
 

Recently my 2003 expedition (8 cyl, 5.4L) was runing rough :-arrgh and had two codes registered a day later (P0172 & P0174). I found out what the codes were :-X21. I looked under hood and found that my air filter was not connected:-arrgh. I have bought a replacement airfilter, however the air filter assembly (plastic cover) is missing, no longer there. Would anyone know the name and part number of the cover where the filter is housed.

This might help:

TascaParts.com

Air Intake Cover
 

Thanks, that is exactly what I needed and it was all under $40 total with shipping. :-X04