IndyJimW

If your Avanti is like my 1987 Avanti it has several hot wires supplying the interior. I have seen problems with these wires having loose contacts at the firewall plug. I would start there. Good luck, Jim Wood

You could also try one of the fuel tank cleaning and sealer kits. Amazon has one by KBS Coatings

Shifter is Monte Carlo. I remember something about Oldsmobile parts for the shift gear positioning slider in the console. Good luck, Jim

Check out bulb part number Sylvania 891. Its a fog lamp or high mount brake bulb. My Auto Zone stocks them. Good luck, Jim Wood

Radio should be in a metal carrier. Remove bezel then you use a radio tool on each side to remove radio, Good luck, Jim Wood

This bulb has been pulled from its socket which is part of it. PC194 is the part number. Good luck Jim Wood

Charcoal canister for vented gasoline from fuel tank and carburetor. Good luck Jim

Why would DOT 5 foam in a closed system?