My wife's 91 940 turbo wagon has been idling high for a few days. It seems to want to sit at 1200rpm and will remain there until fully warmed up, when it returns to normal. There is no hunting, turn the key and right up to 1200. This morning as she loaded up the kids I opened the hood, and just because it was sitting right there I unplugged the IACV and the idle immediately dropped to normal. I plugged it back in and she remained steady right where it should be. My wife drove the car once more in the morning, and reported no high idle. That is good, but I would really like to know what might have caused this, because I am sure it will return soon enough, and how just unplugging the thing fixed it. Could it be some weird electrical thing, or is my IACV just in its death throes?

Thanks in advance