The one I replaced to fix my intermittent stalling problem is the fuel injection temperature sensor. It is the last one on the engine, the one closest to the windshield. You can actually test this objectively, I only tested it subjectively. I pulled the wires out when the car was warm and nothing happened. I had expected some glitch in the RPMs, so I replaced it. And the problem was gone.
It is also called coolant temperature sensor. The resistance values should be about 2.5 to 3K at 20 deg-C and about 250 to 300 ohms at 80 deg-C. I am not absolutely positive about the exact numbers but the change should be approx a factor of 8 to 10 when car temp goes from 20 deg to 80 deg-C.

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Saumil S. Patel