Cylinder 4 misfire. Google the code to get links for causes, trouble shooting and fixes
IIRC, Autozone, O'Reiily and or Harbor Freight have kits with various sized push pin plugs.
https://www.obd-codes.com/p0604 for info
Most likely the steering column intermediate shaft. It's around $80 from Amazon for a Dorman product. Not very hard to replace. There are YouTube...
CEL? If you don't have a scanner go to Autozone, O'Reilly, et al to get scanned.
I use them to hold a pen and pencil. Keeps them from rattling around in the bin where I keep a little notepad and registration and insurance card.
How about using a Cobalt SS/SC wing? Might be able to source a complete decklid with the wing.
As far as covering holes, get vinyl plugs from a...
Check eBay. I was able to locate a new GM ebony leather bottom cover for my G5 GT. All the GM online stores listed it as discontinued.
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