I think I've solved the issue. Generally at an OEM level the three big things you look at are fuel temperature, pressure to the pump (restriction), and pressure to the engine. Obviously temperature was fine. It could make pressure to the engine. I measured restriction. Yikes. Before and after the filter determined that the issue was the filter. It's got less than a 3/8" internal diameter even though it's billed as and has ends for -10AN, and on top of that uses a single mesh element. I ordered a cartridge style filter like my post pump filter- albeit a cheap generic one for a fraction of the cost of the big brand names. Internally it's great. But be aware the -10AN fittings on this one were 10mm (0.040") and had to be drilled out. I noticed an immediate difference. The pump was quieter and wasn't working as hard as before. Restriction was negligible. Fuel pressure was maintained after a long drive (though it's apparent I'll need to be careful on hard stops and turns with the sump with low fuel.)
TL;DR: Avoid the Earl's filters. Buy a reputable cartridge type filter and always check your orifice/fitting sizes.
TL;DR: Avoid the Earl's filters. Buy a reputable cartridge type filter and always check your orifice/fitting sizes.
