so I know this isn’t quite the place to be asking this but I’ve run out of options. I’ve got a 350 sbc with a Holley sniper system in my 80 series and at high altitude especially I’m constantly losing fuel pressure. I’m running a return style system that almost perfectly mimics the factory fueling system in a stock 80. I’ve got an in tank pump and a return line running to the very bottom of the tank. Holley says that my return line is probably too close to my fuel pickup but that doesn’t make sense as to why this only happens above 10,000 ft. I know it’s strange but it sounds and feels like vaporlock but Holley says that’s completely impossible. It’s happened with 3 different pumps, one of which was an external pump, has happened 4wheeling and running up over highway passes. The failure mode is always the same. Motor stalls, fuel pump sounds like it’s pulling air and occasionally building pressure. When it does build pressure (and I’ve verified this with a gauge) it’ll either run for a split second and drop pressure immediately or will run with the specified pressure until all of a sudden the system drops off to 0 and the motor stalls. I’m not yet 100% sure if the pump is shutting off or if it’s just pushing air or something resembling it but every time this happens the fuel prime before start up sounds like it’s not building any pressure and that’s reflected by the gauge readings. Any ideas would be greatly appreciated.