Geez...sounds like you got it running.... I had the sedan 87 300 D...many years ago...You mentioned injectors here and I think I could add something, but based on your short mention of more detail, injectors may not be your only concern.

Original Bosch injector *made in Germany* made for your OM603, may be near impossible to find. What has been available in recent years are rebuilt Bosch injectors utilizing inferior 'India made' injector replacement parts....Results reported are inability to balance injectors properly inducing rough idle and poor performance. Bosch so far as I know, no longer manufactures the injectors. Many people opt to simply have the old original Bosch injectors taken apart, cleaned and then balanced....Often they are far better than the India rebuilds.

I'm not sure who's on Mercedesshop anymore, but a fellow poster named Larry Bible, could share more light. I think you have other issues going on with your om603....but as always, start diagnostic from the las known issue. Be prepared it may go quite far...