NotHappy am I glad to read your post. I have a 96 Contour that sounds like it does the same thing.
My Contour makes the noise when the air temperature is in the 30's or colder. It doesn't matter if the car is cold or warmed up. I get the noise mostly driving on city streets going 25 to 35 MPH and the noise occurs when I let off the accelerator. Hitting the gas will normally stop the noise. The noise is a loud hum that can be clearly heard over the radio. I am on my 4th service dept. trying to figure out what is causing this and this guy is an independent garage because I have given up on Ford dealers.
I just had a new transmission put in this car because the O/D off light would come on and the transmission wouldn't shift properly until I stopped the car and restarted it. I thought the humming noise was connected to that problem but I still get the hum. What concerns me is the humming noise was steadily getting worse and now it isn't nearly as bad. I will talk to the service guy today and if I get new info I will post it.
The main reason they put a new transmission in is because they put in two new converter solonoid packs and both burned out immediately. Too early to see if that issue was resolved.
