1990 300E 2.6 stalls after warm up, guessing it's temp sensor

My 300E stalls after warm up. After startup when temp approaches to 80, idle becomes unstable and dies. I'm suspecting engin block temperature sensor, 'cause when I
disconnected EHA connector just before it dies, it became stable.
However, there are three temp sensors on the engin block. The one with one terminal must be gauge sender. The others are two terminals and four terminals. I'm guessing four terminal one is for the controller. The resistance values accross two terminals are about 1k when the engin is cold The two 1k's are seperated. I didn't have chance to measure when it's hot. Any body knows what value of those should be?
If it's not the sensor, what would be?
Thanks in advance.
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