My best advise would be to seek a good OLD tech with an exhaust gas analyser and experience with inline mech inj.
If you wish to learn this system start by searching the archives. There are many threads on the necessary testing you will need from here. You need to evaluate the thermostatic function of the pump since it often sticks when left sitting. You need to know how to manipulate the linkages to evaluate whether you have a lean or rich misfire condition.
Bosch Master, ASE Master, L1
33 years MB technician