Not a problem with a ford but my daily work hack. 93 Excel...

Anyway, on a hot day, after a period of driving my car starts to run as rough as guts and then finally stall. It will start to do it anywhere from 1/2 - 1 hour of driving

One thing I have noticed, is it has ALWAYS happened on a hot day and when petrol is very low (= <1/8th of a tank). I also noted that it will start to stall quicker if the aircon is on.

I think that it is because the fuel pump gets to hot, as its working hard because fuel is low, and the high ambient temp around it as well... Does this sound plausible??

Some in-tank fuel pumps require the petrol to surround it to keep it cool, and if you have less fuel, less of the pump will be cooled, amd the A/C makes the engine and therefore pump work harder, and as the pump overheats or whatever, it stops pumping petrol and you stall.

I'm only guessing though.

thats what i'm thinking as well, I am going to fill it right up and see if i can get it do the same thing again. 33 is the expected temp tomorrow

f**k 33 now that is hot

coming from a WA person, i don't know if that is sarcastic or not

Of course it is.