Several good points made. I think Daltonmarine offers a good starting point. I'd start at the beginning of the fuel chain supply chain. Are you running off the main tank or auxiliary portable? Injecting oil or premix?
Assuming the primer bulb is still fully pliable, does it collapse at all when it cuts out? If so, that would likely indicate clogging between the tank and the primer bulb...or even a clogged or closed tank vent.
Here's what I found once that gave the same symptoms (my guess on this is that at some time silicone was used as gasket for sending unit which broke down and sunk to the bottom of tank) obviously no screen on my pick up tube:
Then check for water in the separation filter. Might just suck some fuel out into a clear container prior to the separator and see how it settles out...
No clogs, no water - work your way up to the fuel pump, fuel lines, then on to carbs... Bushwacker's logic makes a lot of sense if the problem isn't prior to the carbs.
Good luck, keep us posted