I’ve got a very similar issue but mine sounds like a rattle. I’ve had my truck back to the dealer numerous times for this and they say they’ve fixed it every time I go to pick it up and then on the way home the sound reappears. I think I’ve got mine narrowed down to the exhaust but unsure yet. Mine is at the same RPM range as well and will make the rattle when I first start the truck in the morning. When sitting in the cab, it sounds like it’s coming from behind the dash but that’s not the case. Sent from my iPhone using Tapatalk