Idle/Stalling issue with '99 5.4L Expedition

[mach_u]

My dad has a '99 Expendition with the 5.4L in it with 130k miles. He's just started having a problem where when he starts it or stops for a light, it starts running a really low idle and a lot of times will stall out on him. Once he puts his foot down and gives it some gas it's fine. Any ideas as to what this might be? Thanks!

 

[stroked61falcon]

replace the idle air control valve. also make sure the vacum line for the pcv valve doesnt have any holes, real common for the rubber elbows to get large holes in them causing vacum leaks and idle problems. but most likely an iac.
by the way im a ford dealer tech. just sayin.

 

[spike_africa]

yeah i was going to say its its stalling has to be a problem with vaccum or the IAC. Mine failed a few times on my 99f150 from oil from the PCV system.