Not so much dead but not right at all

[Edubcee]

Hi
I've had a play today and thrown a new diesel filter on with some atf in it and its now running on 5and3/4 cylinders ish
Its on 6 cylinders but rocking in it mounts noticbly, in the car feels like your being rocked rather harshly by a gang of yobs
Tried cracking off an injector while running and each one dropped out as each pipe was cracked
I did notice that the old filter had a fair amount of brown snot like stuff in it and was only half full of fuel so not sure if that means I've got a line blocked up with gunk or something maybe from the tank
Any more help will be appreciated as at the moment I have a rather large Volvo shaped door stop
Kind regards
Eddie