not raving over 2500 revs loads of smoke??

hi i am working on a x reg nissan cabstar 2.7 mechanical injection, we have replaced the turbo, had the injectors reconditioned and fitted a new exhaust, it is still running really poorly and will not rev over 2500 revs 3000 if i am lucky, it is fine on idle?? a lot of people are saying remove the banjo bolt to find the metal gauze filter? can anyone please help and tell me where this is located a picture would be even more help?
infact any suggestions would be so grateful