I never had a problem keeping up with 80 mph traffic on California Freeways with my E300D.Reset ECU = clear codes and reset to stock values.
Your transmission is electronic and thus "learns" and adjusts to your driving behavior based on conditions, engine feedback, etc.
Yep. Still have the '95 E300D. Mine is the very last W124 (by vin#) imported into the USA and never going to sell it. It has just turned 100K. I'm probably going to be buried in it. When running properly, the '95 is not slow. I've had it keep up with a S430 V8 gasser even off the line.