I believe you had a phone call with AlexO about this where he explained that in his (and my) experience it is quite normal for these cars to idle a bit quickly when warm, under electrical load, when the battery voltage is a bit off and in many other circumstances.
There is no 'easy fix'. Cars are really quite simple - air and fuel go in, these get ignited in the cylinder and power comes out. If it is idling a bit quick you have extra power. This can come from incorrect fuelling, additional air or incorrect ignition timing. Check all of these things, work out which it is on your particular vehicle and then fix it.
The control system for idle is very much open-loop and small changes to seemingly insignificant things can make a large difference. For example a bad earth which changes resistance at high/low temperatures will affect the voltage seen at the IAC valve, this valve is VERY voltage sensitive in its operation. It could be something as simple as a dodgy electrical connection.
Have you flow tested the injectors? Have you done this at various temperatures? Voltages? What is the flow variance with voltage? What is the voltage at the IAC valve when the idle is fast? What is it when it is slow? What are your MAF sensor values when fast/slow?..... As you can see the possible questions are almost endless.
As I say, you need to start at the beginning and diagnose the issue properly before any of us can tell you what to change. Or find a good garage that will take the time to find the trouble and fix it. Or a useful techy friend who will drink your beer and work on your car for you. It is almost impossible to diagnose remotely.
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