Another issue you might consider is crap in the tank. I chased and chased all kinds of ideas on my '48 Packard, and all it was was crap in the tank plugging the pickup. Car runs about a block or two, shuts off like you shut the key off. Let it sit for a little bit, and it fires right up. UNTIL enough suction is created to pull the crap back up the pickup, then it's off again. All it was was a little piece of fuzz in the tank.