2.0 tdi injectors/injector loom

Has anyone had experience of a faulty injector or injector loom on here? Or knows what is more commonly at fault.

Ive narrowed my misfire down to either of the 2, but now its trial and error, i've bought a new loom to try, and if that doesnt cure it then a new injector.

Also, anyone know how easy the injectors are too fit? I know its easy to fit, but a mate of mine said to be careful as sometimes they need proper setting up with a computer?

Thanks for the replies, to give you a little more detail my mates diag machine was set up to show the fuelling to each cylinder, after we found the error code for 'intermittent misfire cylinder 3'.

Cylinders 1, 2, and 4 on the fuelling graph showed the fuelling raising and dropping with revs, throttle, etc. Cylinder 3 was pretty much a straight line chucking in loads of fuel all the time. Occasionally it would drop down but most of the time it seems to be just flooding the cylinder.