Mmm, that's weird. Small leak on the fuel "chain" letting a bit of air in?
Hi, just following up:
Indeed the suction side of the fuel system wasn't completely air tight, I discovered small leaks on junctions. Temporary repairs stopped the jerking
‘01 Peugeot Partner 1.9 D, 5W40 A3/B4, 262000 Km, running on WVO
Wife's '19 Suzuki Vitara 1.0 Boosterjet (TGDI), FACTORY FILL, 6000 Km
Backup's ‘01 Toyota RAV4 3-dr 2.0 VVTi, 5W40 A3/B4, 158000 Km