Very nicely done. Truly, there's little excuse for not being at least semi-professional, failing that, nice. Top 20 contributor or not. I suspect, as you suspect, that you are correct.
Most of what you describe sounds electrical (to me). Not knowing a heck of a lot about Sables, I'd see if there are any stored codes in the computer, and get the computer checked out. Freakish things happen when computers decide to go all wonky, and they're extremely difficult to trace, if it's not eliminated as a source of the problems.
The one item that's concerning is the fluid smell. That tells me the fluid's bleeding somewhere. It may be a very small leak, pinhole, even, and it may take a long time for the fluid to go down noticeably. It may also be leaking onto something that's cooking it, and that's why you smell it...although why it's not a constant, I cannot fathom a guess. I know they can do pressure tests on systems to see if there's something imminently about to fail. You may try that route.
Something that just occurred to me...Check for critters. Some of them like to eat plastic, and generally just chew on things. Since it sits outside, near and/or around trees, you may even have some kind of ant infestation or other "visitor".