What are you calling the mounting sensor?
#1 suspect is the coolant temperature sensor (CTS) which is the 2 pin sensor right next to the thermostat housing. They can fail and read colder than normal, and a really bad one will read so cold (due to increased resistance) it can command such a rich condition it can fuel-foul the plugs and stall the engine.
You can test the sensor with a multimeter, or just replace it if it looks old. Also inspect the wiring to it, and the ground wires that attach on and next to the thermostat housing bolts.