Metal inside?

Good afternoon,
I have a problem with a 2010 Chevy Impala, whenever I turn the car on, the rpms go up and down like crazy. The engine also shakes a lot. I think it is a problem with an injector, today I pulled off the valve cover and on one of the six holes that were exposed there was what seemed to be like broken pieces of metal or shredded metal. What could this be and how can it be fixed? Also how could it be related to a spark plug coming out crooked from the part that goes in first, all of this is just on cylinder 6, the hole with the metal in it and the spark plug coming out how it did.
Thank you

Bore scope or remove cylinder head to inspect for damage.
Replace related parts or source viable engine.
Not much to go off of with just this picture, just speculation.
You could perform a relative compression test or a manual compression test to confirm bad cylinder but physical metal is never a good sign.

Is this a 3.5 or 3.9 L ?

3.5l

The photo appears to show a passage in the upper intake/plenum, not a head beneath the valve cover.

https://www.automotiveforums.com/vbulletin/attachment.php?attachmentid=57077&d=1684042968


Do you have a photo of the head with the valve cover removed? That would possibly be more revealing.