One possible solution is to replace your fuel filter head with a new OEM filter head. I know you rebuilt yours, but that sometimes doesn't work well enough. New filter head with new filter is in the range of $135 (or less). Not a difficult job. Of course there could be other causes, other leaks (suction, not pressure) anywhere in the fuel line from inside the tank to the fuel filter head. Does your problem seem to be more prevalent with a low fuel level in your tank, or high fuel level, or doesn't make a difference?
2008 Silverado LT, CCLB, Edge Insight CTS
2009 Arctic Fox 29-5T, Silver Fox Edition, Onan 3600 LPG generator