Of the 30+ vehicles I've owned the cold (high) idle lasts for a while. Of course the colder it is the longer it idles high. However on the newer Taurus's, the longest it's idled in 270k miles is about 15 seconds at about 0°F. Even at freezing temps (and obviously above) it idles at around 1300rpm for like 5 seconds and drops down. There must be a reason it's been designed this way, does anyone know why? Cold idles generally slowly creep down to normal but these just drop right down after a short time like a sudden fuel cutoff. The old Taurus's will cold idle for an hour it seems.