I finally got round to fitting the new injectors I bought of Ebay about a year ago on Saturday. The ones that came out had a build up of carbon around the injector holes, some more than others.
They've made quite an improvement. The engine used to feel a little strangled at higher revs and wasn't keen on revving out, sometimes chucking out puffs of black smoke, like it was miss firing. It now revs out freely and with much less black smoke.
It's a bit nicer to drive now and you can make the same progress with a bit less throttle, so hopefully MPG will improve too.
I was a bit nervous about fitting them as I've never really worked on a diesel until now. Having heard the problems some people have had with bleeding injection systems sort of put me off. The job was a piece of cake though, hardest part was getting the old ones out.
Well worth the cost.