I've got a 92 Jetta that seems to be vapor locking. It runs fine when it is cold or you keep moving. But sit in traffic and let it get hot and it starts to stall. I can hear the fuel pump start to whine when this starts to happen. If I can get the fuel flowing enough it start running right again. I've changed the fuel filter next to the tank. Anything else I can do? The car isn't over heating.