There is a lot of fuel pressure right at the carburetor inlet after it cuts too. Electric fuel pumps are good pushers but do not do well pulling the fuel. Try relocating your electric fuel pumps as close to the fuel tank as possible. Keep them as low as possible also. Make sure the tanks are properly vented so as to be sure you are not forming a vacuum as you draw fuel out.
Engine starts but tends to die or stall out when trying to accelerate.
Have changed the fuel filter, but it didn't help. A local mechanic here in Sitka, AK told me it probably needs a new carburetor - apparently, there's some kind of electronic devices in the carburetor that cannot be fixed here. Have your mechanic check for the availability of a rebuilt carburetor. Also, your local Chevrolet dealer should have the individual parts that go in the carburetor. This van has been having problems off and on for approximately 6 months.