Our '90 300TE M103 has no intake air temperature sensor (or EGR, but it's Australian delivery too). My '90 190E 2.3 M102 has an air temperature sensor on the air filter that someone previously disconnected. I checked the manual and it shows that for my model year the M102 should have the sensor but in this case it is connected to the EZL ignition module not the KE ECU. Apparently the ignition timing gets progressively retarded at higher ambient temperatures. There were many subtle changes from year to year.

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107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.