Q: Why does my car have trouble idling when it's started in cold wheather on 2000 Audi TT Quattro

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I start up my 2000 audi tt, when the outside temperature is around 20-30 degrees F, and the rpm meter moves to about 600 rpm's then jumps to about 1000, and does that reapetedly,(about every 2 seconds)until I drive it for a little while, then this occurs less often, until I start it up again in cold weather. I'm really curious to know if that means that my o2 sensor has failed or if my car's just getting old. It currently has 152000 miles on the odometer. If it may be something else, please inform me as well.
(1) Answer
As you tt has coil packs on each spark plug, get the diagnostic to check whether they are all working properly.
The packs sometimes become intermitent and cause irregular running.
Just replace the faulty one - do not replace them all at once as the others can last longer.