The car is an '85 190E 2.3 8v. The changes were just adjusting the idle mixture as stated in other threads. I also removed the vibration damper disc that goes parallel to the front flex disc in the driveshaft.

Perhaps this will help:
Today I took a quick test drive. I first put the transmission in "neutral" and pressed the gas pedal hard and the RPM gauge reached as high as 6K, I assume it didn't go any further perhaps because the engine is old, I think.

Then I drove for like six miles and the car did not go faster than around 55 mph, and the RPM was around 2.5K, about half the "allowed" rpm in neutral, no matter how hard I pressed the gas pedal. The car just feels too "heavy" after 40 mph but slowly it reaches 55 but no more.

WHAT THIS APPARENTLY MEANS
That the speed is not limited by the RPM, there must be something else that is stuck or not aligned correctly or not correctly set

thanks fahrgewehr2 for the comment