Just noticed this a couple time since the weather has started to drop below freezing. Typically it will cold idle at 1500-1600 for about 15 seconds then drop to 900 or so until it warms up. A couple times I have noticed that upon immediate start up it will immediatley cold idle at 1100 then drop to 800 or so. First off let me say that the idle is smooth and doesn't fluxuate at all. I recently changed plugs and coils @ 60000. I have had to park the car outside for the last couple months for a remodel but that's the only changes. I've kept up all maintenance as required. Maybe the idle control sensor starting to go? Thanks.