[harasn]

I have had this before on fuel injected cars. I suspect your fuel pump is on the way to failing. It seems that when the fuel through the system is at normal temps, all okay, as soon as fuel temp rises, due to higher than normal under bonnet temps, and a fuel return from the engine bay to the tank, the pump starts to overheat and not pump properly. Let it cool down and all good. Although this is pain, its better than it suddenly stopping as they can also do!