What about this?
I'm no mercedes injection specialist, but on many other systems, the temperature sensor has the largest effect on the fuel mixture. A cold engine indication would be a high resistance, which an open connection would give you. I have seen this problem (open connection or defective sensor) on both throttle body and Bosch k injection systems. Possibly something to check would be the integrity of the wiring from the temperature sensor to the ECU. Both of these conditions should eventually cause an error code, however. Just something to think about...
'82 300D/4.3L V6