Based on your description, it sounds like you have an engine vacuum leak. That is the first thing I would recommend looking for.
Here is a link that explains how to locate and repair a leak:
Try this and let me know if it helps. If you are unable to find a leak, let me know. Also, in the event no leak is found, record the noise and upload it for me to hear. However, what you described is exactly how a leak would react.
Let me know what you find.
Friday, May 26th, 2023 AT 10:44 PM