I had a '90 GM car, did the same thing, replaced filters, etc., nothing changed, then discovered it was the coil pack in the top of the distributor. Easy to replace and I never had another problem.
But, your issue does lean towards a bad fuel filter. Your clogged filter will slowly let the bowl fill, after you start the MH, the bowl empties faster than fuel can seep back into the carb bowl, and you run out of fuel.
An easy way to diagnosis a fuel problem is:
Start, run until it dies,
then disconnect the fuel line from the carb, place a quart size plastic bag over the line an secure tightly with a rubber band,
remove the wire from the coil (you don't want to start the MH)
Crank and watch the fuel flow into the bag. If you get a lot of good squirts filling the bag in just a few seconds, then fuel flow is OK, look elsewhere for the problem. If fuel to the bag is very minimal, then you have a clog somewhere in the fuel line or filter.
