It sounds like the moosing problem, sounds kinda like a foghorn, right? I just had the fix done at my dealer under warranty. This fix
http://www.contour.org/FAQ/FAQ.php?s=probs&displayid=15 is exactly right. I called my dealer and had this page printed out when I called. I explained the noise (although the guy on the phone didn't know of the term "moosing"). I told him I think it's the IAC Valve, and he said "yup, happens all the time". He made it sound like half the ford V6's do it. You'd think there'd be a recall. If you're still under warranty, I'd just take it in (I had it in at 8:00 and back at 5:00 that evening). I had it fixed about 2-3 weeks ago and haven't heard from the moose since.