Here is a clip of the noise. Starts usually 3-5 min after startup at idle. It goes about 5-10 min then noise disappears. After 5-10 min of around town driving noise returns as a quiet sound then builds. Have noticed it stops Under normal acceleration but persists through rpm up at an idle. New alternator and belt 11/2/21. Removed belt and spun all pulleys they all spin free including the fan. This noise will eventually go away after sitting at idle for about 10 min and you must drive it to get it to replicate the noise. I’m pulling my hair out here, I did do a quick carb cleaner to the vac lines and didn’t get any engine rev.