1990 Stanza. Overdrive shift at cold temps and spedo very erratic at all times. Any suggestions

Could be your VSS (Vehicle Speed Sensor) AKA Speedo sensor.

Hope not though. $200 at Nissan.

Now in the beginning I though Engine Temp sensor but you possibly would have gotten a 2500rpm fail safe. Meaning the 'ol KA24 would have cut off at that engine speed. It could be a little of both maybe:rolleyes: