I think you've covered all the possibilities.
Mine starts immediately when warm.
When cold it takes a few turns of the crank but never fails to start.
Lately seems to start quicker when cold.
TORS installed and appropriate map also.
I suspect you're getting some sort of vapour lock, try and keep your fuel lines cool..........sorry my 2c.....as I've said you've already covered most possibilities.
Mine starts immediately when warm.
When cold it takes a few turns of the crank but never fails to start.
Lately seems to start quicker when cold.
TORS installed and appropriate map also.
I suspect you're getting some sort of vapour lock, try and keep your fuel lines cool..........sorry my 2c.....as I've said you've already covered most possibilities.