I would ignore what you read. Unless it comes from a Landrover manual or similar.
There are no quick fixes, and snake oil is usually ineffective. You need to keep on working through it until you find the problem and fix it.
First thing is to make sure that the water and oil are now separate, and that the level of both stays constant.
Once you are sure about that, if there is still an issue with the running, go through the usual things bit by bit. Air filter, air hoses, fuel filter, lift pump, engine timing.
If every thing else has been checked and is good, then is the time to worry about injector pumps. A pump will usually be leaking diesel all over the place long before you notice any issue with the running of the engine.