Well, to update, apparently the previous owner had either put in a 180 t-stat or it was a defective original unit.
The PN of the one that I pulled out is E9DE-8575-AA.
The PN of the one that went in is YF1Z-8575-BA.
It ran very cool in the summer and extremely cool in the winter. Now, with the OEM unit, it runs at normal temperature (below the N in NORM) and I actually get heat out of the heater.