sound like my old 205 diesel wen the fuel heater went holed ,there may be the slightest crack/split in a fuel line or joint suckin in air you end up with a stream of bubles in the fuel, se if you can fit if temporarly a clear fuelnline just before the the pump look for bubles in fuel, also i think the turbo controles from the pump check the vacume controle lines for splits, was the pump suplyed with the minimum/anti-stall settings set corect for your car ask the suplyer about this.
lee- plant hire mec., October 2013