Lunging? Could this be surging? Caused by fuel volume or pressure drops under load/demand?
I had to physically CUT OUT my fuel filter (1995 pre-evap NAS D1, manual trans) because it was basically welded to the fuel nuts. So I removed the entire line and ran teflon/stainless from just upstream of the filter...all the way to the engine compartment, where I mounted a *large* screw on filter (looks like an oil filter but does not have a bypass). By the way.. that thing had to be insulated because the underhood temps are off the chart here (NC/USA) in the summer. While this fixed my surging problem it exposed the next weakest link: the fuel regulator began to fail shortly afterward.. so that was replaced next.
One other "surging" problem I had occurred *after* replacing the fuel pump: the pressure line *blew out* due to it not being an actual high pressure hose; I am referring to the in-tank host that connects the actual pump motor to the plastic/metal egress fitting. Cheap crappy hose that came with a "high quality" pump. Live and learn.
By the way, if anyone has a cross reference to other pump motors, can you please drop it in here? The stock non-evap (1995 NAS...and I think 1994 and earlier non-NAS V8's) is the ESR3926. I am looking for alternatives (ford/GM/Toyota/etc) in case of "not in stock" situations.