If you have a model from 2004-2008, the air filter is on the right side of the engine compartment in its own housing for 4.2 and 4.6L models or in the center for 5.4L models. To replace the filter on 4.2 or 4.6L engines, simply loosen the clamp securing the inlet tube, release the housing clamps, separate the cover halves, and remove old filter, while on 5.4L engines simply release the clamps; slide the tray assembly outwards then remove the filter. For models built between 2009 and 2010, firstly loosen the clamp disconnect the MAF sensor, release the housing clamps then separate the cover before removing the used air filter. Inspect/Clean/Replace as necessary; Do not drop anything inside the housing when working. Never drive without an air cleaner. Wipe down the outside of the case with a clean rag after changing the element.