[DK on the road]

I thought i was low on fuel in my main tank and I had sucked air. It was warm out and I was running the for the air conditioners.  It was running and I was down to about 15% on my fuel tank.  I slid in all slides and refueled.

1) is the fuel pick up for the gen set higher than the engine ?
I have known this to be at 25% on earlier motor homes 

Now full, it ran fine. I even changed the filters, and added gauges to see pressure at the pump and suction prior to my new Racor filter. 

The next trip, again now at more than 1/2 the tank full, it slowed and stalled again. After my wife came and found me and told me it stopped, I went back to try and restart it. I went through 3 start cycles, while I held the prime switch on and it tried but wouldn't start. I decided to bleed all injector lines and hold the prime switch and after 3 start cycles it still didn't start. The next start cycle it started to get fuel and after closing each (and making a mess) it started.  If I hold the prime switch on when it slows, it will regain RPM and continue to run.  I have power to my fuel pump at all times, as measured with a continuity light, while its stalling showing 5 PSI just prior to the injection pump. 

2) is 5 psi enough ?
3) am I over riding the electric shut off switch by holing the prime switch on ?

Is my electric switch at the injection pump failing ? It looks newish by a previous owner.

Is this an electrical problem ? I once thought it was a fuel delivery problem

Your thoughts are appreciated