I have a 1993 240 with an odd constellation of symptoms. I've been getting a 1-2-3 trouble code, indicating a fault in the coolant temp sensor, and associated rough idle and poor MPG. However, the problem only presents itself after the first 15-30 min. of driving. When I clear the code, it doesn't come back until about this point, and its been doing this consistently. I've replaced the sensor itself (the correct one, I realize there are 2 temp sensors) and the connector to the sensor with no luck. Does it have to be the wiring or could it be something else? Thanks for your help.