po128 code BEYOND FRUSTRATED

I have a po128 code (low coolant temp)
preventing me from passing state inspection.
I've spent over $2000 replacing the
thermostat, thermostat housing, all
appropriate sensors, flushed the coolant
system etc. I've replaced the thermostat itself
2x to make sure I didnt have a faulty one.
we've gone through all wiring and connectors
to ensure there are no shorts. this car isnt
worth putting money into replacing the PCM
...I'm not spending another 2k on this when
its operating at perfect temperature, and the
vehicle passes all other aspects of inspection
. Is it possible to update the PCM software to
avoid spending way too much money on
replacement? HELP!