Rb30 Patrol Consistant Rough Running

[Patrol30]

I have a Nissan Patrol that I bought and would barely run with an extremely bad misfire and running extremely rich. First I changed plugs, leads, coil, fuel filter, distributor, ecu. I finally decided to take out injectors and spray injector cleaner through them whilst pulsating them. Put them in and the problem was gone for a while until it started chugging under load again, after 2000rpm smooth as anything. Took the tank out and saw the fuel was horrible and tank was rusted, lined the tank, allowed to cure and injectors and line were full of sludge, I took the injectors to be rebuilt and tested, put the fresh tank, lines, injectors, filter and fuel all back in now has a vibrating miss which is now a very smooth miss and sounds and feels like to every revolution. I'm at whits end and have exhausted all avenues that I have thought of. It starts fine, idles a little vibratey, and can rev up but a chunky rev, with a massive lack of power. Still worse under 2000rpm but will still flatten out a little over 2000, definitely doesn't smell rich any more though I checked all the plugs once again and they all were black powdered, I cleaned them and took it for a drive, no difference and took them out again, black again, now i know this could be because the car is running rich which would explain the plugs carboning up but it sure doesn't smell rich and also it is too lumpy and consistent to rev to be the sole problem, imo. I'm really running out of ideas, I have searched high and low through similar issues but to no avail, can anyone point me to what may cause such a scenario?