That is a bad situation with a diesel engine, but not unfixable. First things first, Im not 100% up to date on that engine platform, but I can still help.
1. If there is a fuel filter it must be replace2. If there are fuel lines they must be replace3. Any lines or fuel tanks that can't be replaced need to be thoroughly cleaned and all tube/orifices need to be blown free of obstructions4. And unfortunately injectors need to be replacedThe problem is that fungicides can corrode metal very quickly and have almost 0% lubricity and can damage the injectors