Bad hot starting when parked by seafront

I have a problem hot starting my car when parked
near the seafront but is ok at higher altitude it has
only 16.5 k miles on it. It has been back and forth
to the dealers and they can't find the fault they
have changed the fuel pump and pressure
regulator it never shows a fault code.
It fires up and idles erratically for a few seconds
and then shuts down.
If I use freezer on the temp sensor and throttle
body it fires up immediately and then runs perfect.
Sometimes flooring the throttle will get it to run.
This car on its first service 3500miles had sparking
plugs and air filter which makes me think there
was problem from new.
I am the third owner from new your advice would
be appreciated.