Over the weekend I pulled the pump and took it apart. The pics are below along with a short video of the rotor on the shaft. I found some debris on the face of the rotor as you can see in the pics, and looks like some grit got in there. Not sure if the rotor is supposed to be moving around so much on the shaft before engaging, but that is what it was doing.

Wondering if the something internal in this pump caused the zero pressure but the fact that it is intermittent is a mystery to me. I ended up pulling out the sending unit, the sock filter was clean of any debris but I blew it out anyway. I checked the filter before and after the pump, both clean and clear.

I swapped the pump out for a Mallory 110 unit and so far so good.

The big difference between the Mallory and Holley HP is that the Mallory is showing steady 8 PSI on the gauge while the Holley only got to about 7. Both pumps are designed to run w/o a regulator but is 8 PSI too much? My idle is up a few hundred RPM since this pump change, could I be getting gas going past the needle and seat?

https://youtu.be/chvvG6O6UEs