Pop bottle-like noise

Inconsistent noise (sounds like you’re blowing in an old pop bottle) at around 34 to 45 rpms and disappears when accelerator pressed. Also notice noise when using cruise control and noise will disappear if there is any slight acceleration or deceleration. Car has 257,000 miles, well maintained, 8 month old tires. Thanks

That would be 3400 to 4500 RPM…

I’m guessing you have some sort of vacuum leak. Can you hear it very loudly if you have your head under the open hood? If so, you can use a short piece of hose as a stethoscope to locate its source. If it’s big enough, you won’t even need the hose.

This noise only occurs when the car is in motion…when I’m driving. The noise is inconsistent therefore, I cannot produce it when I have a mechanic in the car with me. Very frustrating.