2000 F150 5.4 over heating
 

2000 F-150 5.4L with 20,000 miles. Cylinder Head Temp Sensor errors come up. Replaced CHT sensor and actually checked temp with temp probe with no over temp but error still comes up after warm up-about 15 minutes and engine goes into fail safe cooling.
Instrument panel temp gauge comes up normally and after about 15 minutes goes from normal and spikes quickly to hot.
PCM had to be replaced about 2000 miles ago after it just went bad. I have checked the voltage feeds to the PCM at 14.2VDC while running, the manual shows the volts during run/start at 12VDC and PCM seems to get pretty hot. Volts going to the CHT probe starts at approx. 3.8-4VDC and I can watch the volts drop to about .65VDC at normal operating temps but the voltage suddenly rises to 4.8-5VDC at the CHT probe and goes into the fail safe cooling.
Thanks for any help, Ron

can it be the problem of chip on the circuit card?
why not ask Ford technology service?