Alright. I no longer have any idea what's going on. So, if you know what might be happening here, I'm all ears:

I've got a great little 1991 Civic DX, 1.5L manual. It's never let me down and I love working on it.

Stalled on the highway a couple weeks ago and I couldn't get it re-started. Over the years, it's had a bit of a personality where it chugs and occasionally stalls at a low idle, or when very slowly accelerating from a stop. If I'm sitting still, I'll turn the key to full off, give it about 30 seconds, and it'll start right back up. For whatever reason just re-starting without turning off never seemed to work.

So since it stalled on the highway and I wasn't able to get it started at all, here's the list I've replaced or completed:
- main relay
- fuel filter
- plug wires
- spark plugs (the old ones were due, but not overdue, and all four were pretty fouled with burned oil and had oil in the wells)
- spark plug well o-rings and valve cover gaskets
- and fully charged the battery

At this point, if I let it sit until it's cool, it'll start right back up with no trouble. Then once it warms, it starts to run a bit rough, eventually chugs, stalls, and then I can't get it started again - spins a few times, then kinda sticks, then spins a few times, and kinda sticks again.

Any ideas??