Hello forum, new here.... I have a new to me '02 GT 5spd that I have been doing maintenance on. Oil change with Synthetic Mobil 1, with one quart replaced with Engine Restore. New Motorcraft plugs & coil boots, Lucas fuel injection cleaner. The problem is that fairly often, the idle kicks up to about 2600 rpm & will not come down. On the highway it's not noticeable, but driving through neighborhoods....it's too high. When at a stop, with clutch in......it sounds like I'm revving it high. Replaced the idle control sensor, & the indicated air sensor (both on the throttle body). It still does it sometimes...... Any ideas? Thanks

 

Ok....sorry for jumping in & not finding this earlier, but I think I found my answer....

How To: IAC Rev Mod (Fixing the hanging RPMs) in the STICKY's

 

That may or may not fix your issue. I'm honestly not sure. I think the reason most people do that mod is because of personal preference of the sound of a rev.

Oh how to describe this over text...

Let's say a normal car when you rev it sounds like "rrRRRUUUUUMMmm"
Well a 4.6 sounds like "rrRRUUUUUUUUuuuuuuuuuuuummmmmmmm"

Make sense? Without doing this mod the rev comes down over a period of say 2 seconds as opposed to like half a second.

To me it sounds like you have a problem somewhere else. Prior to doing this mod a 4.6 idles normally (i.e. doesn't raise rpms coming to a stop).