1989 Cutlass supreme 2.8 105k miles, starter will not crank

A couple weeks ago I was driving for about 15 minutes, pulled to stop sign and the car died. Starter would not respond to ignition. Let it sit for a few hours and it started. Recent plugs, wires, filters, pcv valve replaced, has valve gasket oil leak.

A few days later engine died while driving aprox 40mph, restarted with no problems.

A few days ago after sitting for 10 hours or so, turning the key produces no response from engine/starter. Gauge shows voltage of 11.8.

I have a fairly new 78 month battery as I have had issues with batteries dying before ( battery replaced as bad by vendor)

I've been told to check relay, starter, fusible links, and that I might have a short in the starter that is killing the battery.

I am new to working on cars. And at this point I'm ready to push it into a landfill, so I figured I might as well take a swing at it.

I searched the first 12 pages or so of cutlass supreme questions but didn't find anything that seemed to match what I am experiencing.

Thanks in advance for any advice or pointers!