Would you prefer some good advise on how to find a competent technician?
We are running in circles because we only have qualitative answers at best. That is except for one test: putting fuel into the intake. This is the simplest, most defining test that can be made with no tools or experience. it shouldn't be hard to produce a reliable answer.
You have done the test and the results tell us with a more than random chance that adding fuel won't make a difference.
And again we are talking EHA and plugged injectors? Our fuel test does not account for too much fuel (I mentioned somewhere a long the line). Before we get carried away, I would suggest removing the fuel pump relay and the spark plugs. Crank the engine over and view whether just air is coming from the cylinders. Replace the plugs making sure they are dry (new would be nice). Crank the car for ten seconds, once put back together. Now try the starter fluid. This is done to be sure that too much fuel is not the case. With thefuel pump relay pulled, even if the cold start injector leaks the fuel will be gone by the end of the cranking. At that point the starter fluid test should be conclusive on the major issue of fuel.
As to the fuel flow, mad has it right about the quantity of air determining how far the plate moves, EXCEPT, that one can place a finger on the plate and vary it as much as one wants (in the adding fuel direction). since I can not imagine fuel being the problem with the test you have done, I believe that mixture control can wait till after the problem is found.
BTW, if you wish to check compression start on the left side (5-8). The only way that compression will be bad is if the chain has jumped and in the over 300 I have fixed it always was that side.
Bosch Master, ASE Master, L1
33 years MB technician