Fuel pressure dropping while driving and under acceleration to zero at idle runs 4 lb electric Blue

Well, it looks like it's turning out that I don't have enough volume to run. The pressure is good but the volume will not handle. The two four barrels is what somebody's telling me. The 3/8 line and 3/8 return does not handle enough volume to keep the float bowls full. It's got plenty of pressure but not enough volume. Thoughts?