I had to get a new used motor… so I bought one with 45k on it. I had all new belts, pullies tencheners, a/c, pcv Valve, intake was cleaned.
When I start the car it idles fine no noise, once it warms up it get this high pitch noise. It’s not a belt, doesn’t fluctuate and when you give it any gas the noise goes away. Here is a link to the sound.
I have found others that have posted the same video but they never posted what fixed the issue
I’m guessing there’s some sort of small vacuum leak. The intake manifold vacuum is much stronger at idle compared to even slightly off idle. I had a Ford Galaxy years & years ago that made a high pitched whistling noise when warm at idle, really loud, and that was caused by the valve cover gasket had a small leak.
You might try a length of old garden hose, or vacuum hose, something to use as a stethoscope to narrow down the location it is coming from. Any of the vacuum hose connections or vacuum operated devices could be causing it, as well as the intake manifold, valve cover, and even the head gasket. It is probably a very small leak to make that sort of noise. Absent any other symptoms, ignoring it may be an option.