I've never seen a VR6 idle high like that with no codes.
Just some suggestions, some you may have already looked at:
*Make sure the throttle plate is closing fully. Make sure the throttle cable isn't holding it open a hair. The throttle cable should have a little slack in it.
*Unlikely, but unplug the MAF sensor while idling and see if the idle goes down and stabilizes.
*Sometimes the SAI system can cause a high idle, but it will throw a code UNLESS the ECU is chipped to ignore the SAI.
*Maybe the PCV valve is cracked?
*I would think you would be getting an "idle adaptation at limits" error code. So its a possibility that you've got some corrosion going on at the ECU connector or at the round engine connector. Look carefully. Corrosion can cause weird stuff to happen and sometimes not throw codes, or throws bogus codes.