My wife's 95 945T used to have a crappy idle for about 10-20 seconds after a cold wintertime start. It would pretty much stay around 800 all the time. Then I found a TSB which references this problem as being related to lower vapor pressure of wintertime (oxygenated, alcoholated) fuels. I installed a new eprom in my ECU ($70 from dealer, 15 minute job), and voila, no more problem. I did notice that from that point on, the cold start idle will momentarily (for about 3-5 seconds) go up to 1000 to 1100 or so, then settle down at around 800-850.