I am trying to get this problem fixed. I have a 1999 expedition 4.6Lw/85000mi and just did new plugs,wires,fuel filter. now truck still runs a little rough. check engine light came on, code p0401 low egr pressure. I replaced egr valve and reset light. light came back after about 20 miles so I replaced pressure sensor, and made sure the 2 rubber hoses were clear andreset light. light came back so i took it to a ford dealership and they replaced the vacuum solenoid. the light came back on after 1 day w/same code. All n all I have spent 300 bucks for nothing. does anyone have any suggestions on what to do next? Thanks for your help