IMO a 140A alternator will NOT be enough.
I installed the E-series battery boxes on the passenger frame rail and then added two extra batteries (deep cycle) to which I connect an inverter (Samlex 2000W pure sine wave inverter) as needed. I then installed a 250A alternator and upgraded the...
I would disconnect one of the two sensors at the connector on the sensor itself and see which gauge changed just to verify your suspicions. I am not yet convinced that they are swapped (or even that they can be).
The coolant sensor may be the easiest to get to.
A scan tool that pulls the PCM data would be HIGHLY helpful. With it you can see what is actually going on with the sensors.
Torque Pro on a smartphone is a good tool for pulling (and watching) PCM data (PIDs). It is a pretty good tool for pulling codes as well.
IMO ForScan on a laptop is...
These dash gauges are SEVERELY dampened in their response/indication.
Just some fyi type stuff:
Operation of the engine temperature gauge (coolant temperature):
When the gauge rises off of C to the lowest mark of the "normal range", the coolant temp is apprx 140 to 142 *F
When the gauge rises...