Engine fades and then cuts out completely...

[Willie]

It sounds as though you are suffering from fuel vapourisation.
If this is the case then you should hear the fuel pump start
to tick more and more as it tries to pump fuel which isn't
there. Since the weather is now cooler has the problem
disappeared. If not,is your petrol pipe from the pump to
the carb sitting over the manifold? It will get a great deal
of heat there.