Carbking and David,
I was under the impression that the problem only happens after adding fuel to the tank. David, if you drive to the gas station and stop for the same amount of time without opening the tank or adding fuel, will the problem manifest itself?
If it does, then Jon is right about the heat soak. If it doesn't experience the problem, then fill up the tank and see if the problem occurs. If it does, then you'll know it has something to do with adding gas to the tank.
