Volvo Penta stalling after warm-up

I have a 2003 Larson Cabrio 330 with twin Volvo Penta 5.0 GXI engines. I was getting the famous whine coming from the fuel pump and the engine was stalling after it got up to temp. I replaced the pump but the problem continued with the new pump. The old pump and new pump both seem to get hot to the touch. I checked the cooling lines and water is flowing both in and out. So.. I put an inline fuel filter to see the gas flow. This is the video of the inline filter, you can see it seems to starve for fuel then a surge of gas. The sound you can here is the pump, you can hear the difference in pitch when the gas surges to the filter. Can someone please help!? Any idea what could cause this?

Condition of fuel filter/water separator?
Vacuum leak @ fuel filter/water separator?
Plugged or defective anti siphon valve,if equipped ( on tank @ withdrawal fitting)
Plugged gas tank vent ( loosen gas cap to check)

Here is what I have gone through so far:
New pump with filter/water separator (was the original anyway)
It does have an anti siphon, I removed it to check that it wasn't restricting flow so the video is without an anti siphon
Checked all threaded fittings for leaks.

Plugged gas tank vent, I haven't checked this, would that restrict flow? What do I check for when I loosen the cap, pressure release?

Does it seem by the video that air is getting into the line somewhere? It's the last thing I can think of, cracked fuel line between the tank and pump maybe. Should the inline filter be full of gas with no air in it after it's primed and running?

Update: So yesterday I swapped the fuel lines to test if it was a fuel/tank issue. The fuel pump still continued to get hot and eventually starved for fuel still. Long story short I went back to the fuel pump cooling lines. I checked them before and cooling water was pumping through the lines. What I failed to check was that where the cooling water enters the manifold wasn't obstructed. Took the fitting off the manifold and sure enough the fuel pump cooling line port on the manifold was clogged completely solid so no cooling water could enter. So I guess if anyone else is having a similar issue, don't stop at just checking the cooling lines, also check that the water is able to flow freely through the manifold port.