Dodge: stalling after warm up., sweptline dodge, vacuum lines

Question
I have an old 71 Sweptline Dodge D200 pickup, 318 manual trans.  When I got this truck I did a tune up and drove it 1100 miles from Seatle to Los Angeles.  I started noticing it had a little backfire/ bucking problem which now has developed into a stalling problem.  It has been starting harder and when it warms up it just quits.  If I let it sit a few minutes I can get it started again but not for long. I also replaced a coil, several fuel filters(thought I may have had some junk in the lines from the old fuel tank), and a fuel pump.  Normally I would think it was the distributor(backfiring)but when it is parked up hill it won't start at all.  It has electronic ignition, I assume it was converted from points.  So I still believe it is a fuel problem(maybe mixture). Vaccum lines seem okay.  Before I replace the carburator(not too expensive)I wanted to find out if I'm overlooking something?  What do you think?  Rick  

Answer
Rick,
When you say you tuned it up was the tune up complete?Plug wires also?Correctly gapped plugs?This could be a lot of things.I would say change the coil but you have.Have you checked inside the gas tank?I noticed you said old fuel tank just curious as to if it was replaced.Double check the vacuum lines,i know you have but a slight dry rot can also cause this.If all this checks out i'd replace or rebuild the carburetor.