I would make sure your tank is vented properly. Check the gas cap. Mine died on the freeway on day and after opening the cap it started and all was well. I found that my tank bag was pushing down on the cap. Never happened again.
On this issue a roadside fix is put a penny under the cap. If it is the problem, when it stops, on the side of the road, put your ear next to the cap and open it - you may hear a whoosh when you break the seal. BTW that hose is not needed for the bike to run. You can shorten or remove it - potential problem gone.
The fuel line must be level or downhill - any uphill segment will produce the problems you are having.
A bad petcock can be eliminated with a Pingel. A vacuum problem can be eliminated by making the OEM petcock manual. A leaky petcock - Pingel again.
The bike won't tolerate a filter on the fuel line. I have tried 3 of them, even ones made for gravity feed fuel systems.
Have addressed all of these problems with 4 Valkyries.
I wouldn't recommend removing the vent line. I've had my tank full sitting in the sun and had it gush out. It's bad enough to have 1/4 gallon of fuel on the asphalt below your bike. I would hate to think of all of that dousing the bike.
