If your injectors need servicing then 2 stroke oil will not remedy that. Given your pump work done etc, I would suggest if you do not know the injectors servicing history the it is well worth doing them now. Get everything in the system working well, pump, injectors, no leaks, fuel system clean etc. You have done most if it it seems, I would get the injectors done for sure. I have had a set of TD42 injectors serviced that had done less than 100,000km, and they were uneven when tested. Goes to show that they do need regular servicing and do not last forever.