I've eliminated most of those items.
Don't know about the engine temp sensor yet.
Because it is very intermittent, goes sometimes days with no problem - running very well, I'm looking at things that seem like they might be consistent with that.
I think the speed and reference sensors you mention are possibilities. Their connectors at the wiring harness (mine are at a bracket on the valve cover) are all very badly damaged, enough so the connections are not secure.
Also wondering if there's a problem at or around the throttle body.