84 300sd low fuel pressure? Gummed injection pump?

[Knuckleballerr]

I was opening my fuel lines, trying to purge it of air chasing a "crummy power" situation.. (40 mph up a hill tops with 50 mph start before the hill) when I noticed something quite odd.

Let me make clear the air was being purged while the car was on and running so nobody is confused (Yes, I was safe about diesel in the skin. I only did it that particular day because it was convenient). When I'd open lines 1-3 (left to right, from perspective of drivers side) there is almost zero change in idle power. In fact, its hard to tell the line is even open? I feel like I can take the line/s off and there would be no change. Line 4 only has a slight drop in power.. but when line 5 is cracked a significant amount of idle power is lost. This is on a MW-Pump.

Tinkering with it.. I've found what can best be described as a "rusty red goo" on just about everything post lift pump.. undoubtedly from the PO's veg oil use. I've purged this pump plenty of times in the past... seafoam.. diesel purge. But I have a strong feeling that's too weak for this (its quite tough!)

I've seen other's on this forum use a long acetone & gasoline soak. Should I do this? (Is it wise to do it during winter? I don't care about working in the cold but I'm not sure how much temps play into this). I've since fixed the lift pump leaking issue that I think is very much related.

Am I to disconnect the lines from the injectors and send acetone through the whole system and let it soak for a LONG time?

~

Also, I considered on cutting a mark on the injectors.. taking them out & opening them up for a super good clean. Sand the surfaces (except nozzles) with 2000 grit paper.. and put it back together and line up the marks. I might not have a pop tester to see pressures.. but would this be wise? Is it possible to use the injector pump to see the spray patterns?