Ford Escape 2006 Fast Idle- Code 507
 

I have a 2006 ford escape 4cly. It has 26,000 miles on it. I just purchased it. It had set for 4 years. It idles at 4,000 rpm, and when I disconnect the
IAC it drops to 2,000 rpm.

I get a code 507 fast air idle control valve.
I replaced the IAC valve twice thinking one might be bad
Sprayed brake cleaner looking for vacuum leak.No change in RPM
The valve has a resistance of 10ohms when I checked it when it was disconnected from the RCM wire connector..
Cleaned the throttle throat. Checked and cleaned the linkage
Disconnected the middle RCM and get a reading of 17ohms at the white/green wire and negative battery post with the key off.

Ran gallon of SeaFoam in the gas tank drove for 1,000 miles on a trip.

When it gets to 4,000 rpms, I can quickly turn off the key and turn right back on and it will drop to 2,000 rpms.

Can someone help me determine the reason for the fast idle?

Check it out for any kind of TPS (or any other code); check that the TP is about 1.00 volt at closed throttle.
If the IAC disconnected and it runs at 2k rpm, I'd be checking base air bypass in a big way. First, and very importantly, check for any vacuum leaks (like a spongy vac. line fitting or pcv that's got a hole due to rot).
One way to check the bypass air is to disconnect the IAC. At this point, the engine (hot, in park), should very barely run, and it will run rough, but it will run. This puts bypass air (the amount the eng. gets with no IAC) right in the neighborhood of where it should be.
If it's still racing, and the TP circut checks out, then there is too much air getting into the engine, usually caused by 1) a possibly bent/hanging up linkage (especially the stop where it rests at no pedal) or 2) a really, really worn throtlle body. It sounds like this is a good bet. Don't bother cleaning it, as the damage is already done.
Another quick check is to disconnect the linkage at the TB and see if the pedal/throttle cable is pulling it open.
Good lucK!

Escape fast idle
 

I had a similar problem with my 2002 Escape, there's an entry on this forum.
Finally cleared the problem after I removed the large electrical connector that is bolted to the firewall, and sprayed it with contact cleaner. In our case, it would intermittently idle fast when stopping after a short drive, and finally became more frequent. Also, it probably always idled faster than it should, because after the contact cleaner application it now idles below 1,000 on a regular basis. It is a V6 engine, if that matters. Try that !