PO 507 Code High Idle

Ok, here's yet another problem. I am getting a PO 507 - high idle- code. All of the sudden car will idle at high speed and feel like it is off to the races, and cruise control is off. Is this a common symptom of a bad IAC valve? Even though cruise control is off should I unplug the cruise control module to be sure that it is not involved? Throttle body is clean, and plates seem to open and close with no problem. Should I put a little house hold oil on the corner of the hinges just to be sure? What is the easiest way to detect a vacuum leak?

Van has 204,000 miles on it and I purchased it at 102,000 miles with a long block engine replacement @ 162,000 miles.

No oil on the throttle.

Check the linkage for binding, both on the throttle and the cruise.

Unplug the Cruise.

Check for vac leaks with some carb cleaner engine running, spray around gaskets and seals of intake.

Checked everything and still same problem. Changed the Idle Air Control valve and and that was the trick, everything is OK and running fine. Only now the car idles at only at 650 rpm. When replacing the valve I didn't have a tape measurer to get the proper extension. I just extended the cone to match the old IAC valves length. Does the length really make that much difference. Should I go back and make sure that is extended no more than suggested 1 1/8 length?

650 is normal idle. Does it pick up when you switch on the ac clutch? It should move to 800 or so then.

Yes, it picks up to about 800. I guess everything is OK.