w124 running hot (120C) in traffic

[Blown_M104]

1993 300E with 3.2 L M104

On very hot days (temp over 90F) the engine coolant reaches 115-120C when stuck in traffic. It's not 'boiling over' but comes close. When the car gets moving again the coolant temp returns to nomal range. The high coolant temp in traffic basically nulls the AC effectiveness and it becomes very hotinside I want this fixed!

Here's what I've done so far towards resolving the issue:

- Two new Aux Electric cooling fans (& check to make sure they come on correctly)
- New Fan Clutch
- New water pump & temostat
- This past week... a New Radiator and cooling system flush

None of these items has made the problem go away. The new radiator help the most but I'm still pushing 120C when idling for long periods of time.

Am I missing something or is the cooling sytem just undersized for operation in these very high tempatures?

PS
I had this problem long before my blower install, so I don't think that's it.