My wife’s 23 2.3l bronco does the same chirping. It happens usually in the morning. My 23 v6 bronco does not make the chirping noise, so I assume it’s only on the 2.3l broncos.
My wife's big bend, 4 door, 2.3 does the same thing but at 40mph to 45. You also can hear it when it's parked in the garage. It also makes a squeaky sound when you first start it. Her Bronco is about one month old too.