Resolved Grand daughters 2003 3.8 v6 overheating

Rented a scanner from AutoZone. Engine heated up to 210° while gaude showed normal. My infrared readings only showed 180° at sensor and 190° at thermo housing. Temp cont to rise even after fan started. I shut off at 220°. Interior gauge stayed at normal.
Lower hose NEVER gets hot at all nor does rad cap.
Has new head gaskets, water pump, thermostat and temp sensor.

I know you folks are getting sick of this.
I can not find anywhere that explains how the scanner gets the real time coolant temp. They all say there is only a head temp sensor that is not in the coolant flow, which I know.
They explain engine can be toast prior to temp gauge showing hot. Also known.
Where is this magical point for the ECT then?

You guys have been awesome. Problem with overheating solved.
Head temp sensor solved it. But since I had drained radiator the day before and did not bleed air, it got better and worse. Found a thread on a different site that said to fill antifreeze with the car on a ramp or jack stands. The 2002 ford v6 loves to trap air. Also, the no spill funnel is a must. I improvised but got a ton of air out.
Scanner is no help if you do not have an actual coolant sensor and have a head temp sensor. Real time readings don't match up.
Thank you everyone for the input!!