Fuel Line Problem

[Damon]

I've been fighting with a fuel problem for a while, and I think I may know the problem.  My car originally had a TPI, but that was dumped in favor of an Edlebrock 750cfm carb.  I have 2 transparent filters, one before the pump, and one after the pump.  The one after the pump stays full, while the one before the pump is usually empty.  under WOT I have a stumble between 3200 and 4500 rpm, then it sort of clears up.  I originally thought it was ignition related, but after a complete tune up,  the problem is still there (although greatly improved).  I have removed the electric pump from the tank and dropped a 3/8" line in it's place, and there are no restrictions between the tank and the fuel pump.   Which I'm thinking might be my problem .... at idle, all the gas drains from that line back into the tank.  Could this be causing the problem I am having with the stumble?  and if so, are one way valves available that would keep fuel in that line?  

P.S.  -  I don't need a full blown racing shut off valve, just something cheap and simple that I can patch into the line back by the tank.

Thanks in advance.  

[Damon]

Well thanks for all the helpful advice.  <_<

The problem is a blockage in the fuel line caused by excessive scale in the gas tank.  So I have to cut off the exhaust and replace the tank.  

Some advice, if you are putting your car into storage or have to let it sit for a while, go ahead and spend the money on a fuel stabilizer to keep the inside of the tank from rusting.