Erratic idle and stalling in 4.6

[03EBVan]

Hi everyone have been reading posts on here for a while now and theres some great info on this site, this is my first post.

Have a eddie bauer 4.6 with about 210k (130,000miles)
mods are K&N FIPK and gibson cat-back
noticed the idle dropping down to around 500 and then shooting back up to just over 1000 and then back to the normal 750 when not pressing accelerator
happened a few times the first day and engine actually shut off for a split second while going about 60k down a hill and started itself again.
today it started up fine but after driving about 5 min erratic idle started again, this time actually stalling while in park twice.

is this a common problem? fuel filter? EGR?

Thanks for your info

 

[fusseli]

I'd check around the numerous vacuum houses that connect through the intake. There could be a bad leak or it could be the IAC..?

 

[03EBVan]

Ya did some searching and found this thread with some great info
http://www.explorerforum.com/forums/showthread.php?t=375903

Tried cleaning the IAC and TB and EGR port with no success so next is a new IAC, hopefully this will do the trick.

 

[FordFool2]

Ours started to do that last summer and it turned out to only need a set of spark plugs.

 

[rmcknight]

vac leak or cracked intake manifold or bad seal.