my car is a very angry monkey

[jesseborgelt]

I believe my car is possessed by a very angry monkey. My 2000 boxster base developed a constant Eeeekkkkkkkkkkk squeal while driving. The noise tends to disappear when RPMs are above 2500 and does not change noticeably with varying RPMS. The noise also stopped when I was carrying bananas home in the trunk from the grocery store. There is no smoke and no CELs but I believe it may be the AOS. The car must be at operating temperature before the noise starts and is soft but grows very loud over a minute or two. From what I have read, most AOS failures produce smoke and make the oil fill cap difficult to open due to an increase in vacuum. I do not experience these signs but when I loosen the oil fill cap the noise changes and will sometimes stop, while the car does run rough with the cap off of course. Does the AOS seem like the culprit? My other thought was a loose spark plug but the noise isn’t an Eek Eek Eek, but rather a screeching monkey. Are there any other maintenance items I should tackle at the same time? Thanks.