WM Fuel Problems

["Joseph M. Shaw, II" <MikeIIDC@domain.elided>]

HELP!!!

I had put off working on this project for a while, but have a few more
questions.  I got back to work on my '74 Wagonmaster today, and changed
out the fuel filter with one of those new-fangled clear ones so that I
can see what clogs it up as we go.  
To refresh memories, I bought this '74 Wagonmaster with an auto and a
392.  It used to start, and would run for about five minutes, then die. 
After that, it would not start unless filled very heavily with starter
fluid, and would die very shortly afterwards.  Sometimes, I could keep
it running after this time by really flooring it, but it usually died.
Several suggestions came is-I thought the fuel pump, but many thought
the fuel filter, carb, etc.  Well, I haven't touched it for several
weeks, but got back to it today.  Using starter fluid I can start it,
but still cannot keep it running too long.  Watching the fuel filter
that was just changed, I can see that it fills as I crank the engine,
but empties out immediately if I fill the carb with starter fluid and
let it run.  The only way to keep it running is to spray starter fluid
into the carb while it is running.
What does this sound like?  It could be carb problem, but I still tend
to lean toward a pump problem.  I have bought an electric fuel pump, but
didn't want to hook it up until I absolutely had to.  
Should I try that next?  Carb?  What do you think?
Also, this has two different tanks-duals-is it possible to place a good
pump somewhere to "suck" from both, or do I need to focus on one alone
for now?  More ideas/input GREATLY appreciated!

Happy Holidays!!!

Michael