xr-stu, are you using supermarket fuel by any chance? These engines really dont like running on it. I know people say that the fuel is the same everywhere but i work in Dagenham engine plant where we made that engine and i have had a few people come to me with the same problem, so if you are, try using a branded fuel for a few tanks and see if it's any better.

If this doesn't cure it then it could be the IMV (I think thats what it's called) on the fuel pump. They were a common fault on them too. It's held in by 2 allen screws, and located behind the rad. It can be awkward to get to but it can be done.

FYI, the injector codes are printed on top of the injector, only TDCi's have them. If you unplug the 2 pin connector on the top of the injector you will see them. There will be 8 pairs of numbers starting with something like FO.

The injectors on these engines have to 'update' themselves but i'm not sure if it applies to the old TDDi engine too. It feels like its holding back under low load (up a sliproad is a perfect example) for a second then all of a sudden it's ok again.

Col cos1, you say the engine has done 175k miles?

Has it had a new turbo? I'd be suprised if it's the original one to be honest.

Have you checked the turbo actuator?

Dave