fuel flow issue

Okay, I am new to this forum, and have reviewed those answers I could find addressing my issue. I have recently replaced my fue pump, and filter, since the pump was leaking and the housing at the base was cracked. The vehicle ran fine for about 6 week, but when I hooked up my 5th wheel, the fuel filter light cam one. The engine ran fine for about 90 miles and since then, it constantly dies, from lack of fuel. I have checked the fuel tanks and lines, and do not have any blockage. I checked the fuel pump intake, and am getting 40 lbs of vacuem. I am able to see fuel flow with the filter cap off, so I know it is not the pump, tanks or lines. When the engine is running normally, I get about 40 lbs of pressure messured at the fuel pressure requlator, but as the engine starts to die, the pressure deminishes to nothing. I saw a comment about checking the screen in the pressure regulator, and I will do that this morning if the rain ever stops. Any other ideas?

Thanks
Mike