Vapor Lock?

Your not still hooked up to the stock pump also are you?

Are you also still using the stock fuel line fitting on the sending unit? The screen at the end could be restricting, just unusual to only stop flowing fuel at idle.

Hi Angelo
I am using a electric fuel pump.
I am using stock fuel line to the pump, aftermarket line from the pump to the carb.
There is a in line fuel filter that I am going to replace just to be sure.

Rambling thoughts here, but:
Don't think it would be the filter if it was not blocking or starving the car while running.
If the pump was running at idle just before the car stalls and the pressure guage was reading no pressure on the pressure side. The problem should be from the pump back to the tank.
There was no change in pressure with the tank cap off, so that eliminates vapor lock.

Problem could only be in the tank supply line or pump.

Car does not have problem while driving or running so that gets rid of the supply line.

I would guess that the pump is starting to fail. Got another to swap with?

Wish mine was together and I was tinkering with it. Should not have taken it apart until I was finished with the vette. I am carless and having severe withdrawal symptoms. groan

Maybe the alternator isn't charging at idle, dropping the voltage below the pump's minimum operating voltage? Just a thought.

John

Does the electric pump run all the time the engine is on? Occasionally, the use of an electric AND a mechanical pump in parallel will overtax the mechanical pump's rubber diaphragm, rupturing it. This can also fill your oil pan with fuel if the diaphragm blows out in just the right way...