[rgren2]

Pretty sure there is a gauze filter on the banjo bolt on the fuel pump, have you had a look at that?

 

[rgren2]

How about the breather vent on you fuel tank?

 

[rgren2]

I just don't know how that would instantly stop being an issue when the vehicle reaches operating temp? Is it somehow temperature affected?

God works in mysterious ways. Is it able to breathe when cold? Just have to rule out possibilities.