Gary, allow me to add my welcome.
As to whether you should cut your losses and sell, who can know? IMO, the biggest killer of these cars is rust - closely followed by deferred maintenance. I suspect you are finding how expensive it can be trying to catch up after the car has been unloved for a while. However, as long as you are not having to deal with rust, all the mechanical things are fixable. And if you go through the whole car fixing/rebuilding all the mechanical systems you'll end with a unique car that can be both fun & reliable. But if you just fix today's problem without addressing all the other things that are about to fail, you'll never get to enjoy the fun & reliable part.
FWIW, I bought our '84 Spider as a project car. It had sat unused for a few years. I trailered it home, rebuilt the engine, installed a new clutch, rebuilt/replaced all the hydraulics/brakes and put on a new top & had some split seams in the upholstry re-stitched. So, for much less monetary outlay than a 2 year old Toyota we now have a car that is unique, fun, reliable and I know it inside & out.
Now if you had asked before buying we would have advised you that spending a bit more for a well-cared for example would, in the long run, be cheaper. But it's not just about economics is it...?