I think that you need to replace your wiring harness before trying to do any further diagnostic work...

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Current cars:
2000 ML55 AMG, 174k miles
2003 C240 T-Modell, 202k miles
1995 S320, 207k Miles

I think that I need to be sure before undertaking such an expensive task .

I would prefer to exchange what is considered routine tune up stuff, before making the most drastic decision of all. The other things that I will change should at some point definitely be changed. They are part of routine maintenance. Plug Wires, MAF cleaning are maintenance.

Harness is not part of ROUTINE MAINTENANCE AND until I can demonstrate that it is bad, it will be the last part to be replaced .

I know that most people in this forum do not have any respect for dealer mechanics , but my dealer mechanic FRIEND said wires and suppressors first , then check injectors . Last thing is the harness on his list and he knows all about the bad harness in my year cars.

I will build the code reader. But a car that runs great all day,and drives wonderfully and powerfully at 70-100 MPH , and has for the last 2 months with over 500 miles, and no starting problems , idleing problems , (nothing more than a flat spot under hard acceleration at a certain RPM when warm ) and runs fine with a little prodding in the form of a gentle gas pedal , does not make sense to me , to be in need of a catastrophic part replacement IMHO

I think it is most likely to be something much simpler . What that something is , is yet to be known . You stray from your ideology when you say harness .

That is just actuarial parts changing as far as I am concerened , and I thought here we look for solutions empirically , not take semi educated guesses.

Before I throw my money away I will drive the car gently , till I find the solution.