Howdy ya'all

I suspect my gas cap is too tight and wanted to hear from some of the guru's.

At idle and low RPM's around the neighborhood, it seems to run just fine. Once I romp on it a bit, I notice it wants to sputter. It will actually starve for fuel, then die. When I pull over to take a peek I can see where the level is below the normal level via the glass dome. If if pop the cap off and blow into the filler pipe, (my version of mouth to mouth resuscitation) the fuel level in the pump returns to normal and all is good again. So here is what I am wondering. If my cap is too tightly sealed and not allowing the fuel pump to easily draw from the tank when under load? As a side note, I have a cartridge filter before the pump and wondering if that is contributing to the problem. Kinda like sucking on a straw with your finger over the other end.....