It is a 98 and thanks for the info. The wiring harness and computer all came from the same vehicle. I fear I facing an electrical issue someplace but am not sure where to start to look.
For megasquirt stuff, I measured the resistance curve of that rear temp sensor. Basically, as the resistance goes up (tends toward an open circuit) the colder the ECU will think it is. Typically, most ECUs will add fuel under this circumstance.. Probably over-fueling if you unplug it.
Temperature Ohms
163F 379 ohms
70F 2479 ohms
35F 5355 ohms
Ref:
http://www.2rzturbo.net/?p=82