Stalls climbing overpasses - please advise

[dvallot]

My 72 Blazer has a 350 and the original fuel tank. It cuts out going uphill and often will not start when parked. I have had this/these problems with my Quadrajet as well as my Carter AFB carburetors. I have also changed the mechanical fuel pump and the inline filter. I wonder if a wire could be moving and shorting out the ignition? The only thing that makes me think that can't be it is that if sits a while, it will start. Any suggestions are welcome. I hope you all had a great Christmas and that you old trucks are running - Bubba