High / fast warm idle 5ktq

[Ryan Hoitink]

On a recent drive, my car acquired the following problem.  When the car is
even slightly warm, the idle will rest at a constant 3000 rpm.  When cold,
the idle seems to be basically normal, but within a minute or two, it's up
to 3k.  There seem to be no adverse effects in the output/running of the
engine, basically it's like someone were holding the accelerator slightly
down to make the engine run faster.  When I press the accelerator, the
engine speed rises immediately, no stumbling or dead spot.  When I unplug
the ISV, there is no change in the idle speed.  The WOT/idle switch is fine.
The throttle have full range of movement.(not being held open by anything)
When I remove the oil filler cap on the valve cover, no change in engine
speed.  I would normally look for a vacuum leak somewhere, but it puzzles me
that the car idles fine when cold.  Any help would be appreciated.  This
unnecessary "cruise control" is starting to annoy me.

Thanks,

-Ryan