Well, it's not really odd that 90-92's were slower that 86-89's.
They had a second gear start and were heavier.
90-92's were not faster than 93's because 93 300E's are the same as 94-95 E320's - they have the same chasis #, VIN #, and engine #.
1993 300E's / 1994-1995 E320's were the fastest because they all had the 3.2 liter M104 engine.
But in any event, off the line acceleration is not the strong point of these cars anyway.
If you're looking for a fast car off the line, get a BMW.
These cars were meant to cruise at high speeds.
Any of the 300E's / E320's will cruise effortlessly and speeds well above that which you will feel comfortable driving at.
