I have a '69 F-100 and it has developed a fuel flow problem causing it to shut down frequently.  I can look at my fuel filter while the truck is running and only see a trickle of gas coming into the filter.  I have confirmed that that the problem is not a carb/needle valve problem, a fuel pump problem, leak in the fuel lines, or a tank problem, what else could it be?    

This is the type of problem that it doesn't matter which engine you have. 6 or 8 240, 300,302, 352, 390. It boils down to a basic function.

You have overlooked something, or it would run fine. Did you test your fuel-pump pressure? it should be around 4-6 psi. You need a minimum of 4 psi. How old are your neoprene (rubber) fuel lines? Old lines will collapse and shut-off the flow like kinking a garden hose will kill the flow of water Change your fuel lines if you have any doubts. I had this happen on one of my '56s not too long ago.. Your gas cap, does it vent properly?  

i replaced all the rubber hoses and i replaced the fuel pump not too long ago.  do you think that the fuel pump rocker arm isn't being pushed hard enough to maintain proper fuel flow to the carburetor?  maybe the metal dowel for the striking cam broke or came loose inside the timing chain cover.  

How much PSI output from your pump, do you have a constant 4lbs. of pressure?  

yes, the fuel pump has 4 lbs of pressure and the volume is good, i noticed tonight when it shut down that if i take off the end of the fuel line going into my tank, i can feel it sometimes pumping and sometimes not, what would cause that?  that is what has to be shutting the truck down.  

Try another mech-pump, or splice in a 12V electric fuel pump and see what happens. Also, are you sure this isn't a ignition problem, coil, switch etc.?