The 500E's with the M119 engine simply don't get enough air-flow while city driving or stuck in traffic.
Once the 500E's goes above 100-degrees Celsius, the engine management system will add more retard which drops power about 50HP.
What I'm planning to do is install dual electrc fans, with two independent thermostats and power feeds for failsafe operation.
One fan will be set to come on at 93-C and the other fan for 100-C. Optimum is 85-90 C for this engine.
I have a solution of MB citric-acid and MB degreaser standing by, as well as all new hoses and a new thermostat.
1988 360TE AMG