Mechanic(s) couldn't find the problem. I'm kinda a motor-head and I couldn't find it. Spent a lot of time driving slow through empty Mall parking lots and through cemeteries. Even had my wife drive slow across some blacktop cracks (in the cemetery) while I hung on the front end of the Buick with the hood open . . Yes there was a Youtube video in the making! There are only a few places where you can drive slow w/o a Cop pulling you over and asking if there is a problem ( and don't ask me how I know ). Enclave is 2016 with 58,000 miles. Rather than spend more $ trying to find the problem ( cause everything essential is tight and working) I just turn the radio volume up when I'm driving slow. I'm 72 ! Eventually my hearing will get worse or I'll trade the Buick in for a new one! Carpe diem !