A few of us have discussed this issue in a couple other threads (links below). Most notice it when it's really hot. For me, though I don't live in AZ, when I turn the car on after a day sitting in the hot sun, it will immediately idle at 1k. I can sit there and turn the AC on and off and nothing seems to matter. However, if I drive for a bit then hit a stop, it will usually idle back at ~800 like normal.
Does that match your symptoms? Still not sure of the root cause, but possibly where you live, the fast idle state won't go away quite as quickly after you start driving, so it seems like it idles at 1k all the time. Did you just start noticing it recently in the hottest months?
http://forums.tdiclub.com/showthread.php?t=441227
http://forums.tdiclub.com/showthread.php?t=440487