Have you checked the accuracy of your electronic temp sensor? Are you using the engine's OBDII sensor? Are you using the temp guage sensor. It sounds like water is moving in the engine.

To power flush you remove both radiator hoses and remove the thermostat then use a garden hose to flush from the top hose and then the bottom hose, get as much flow through the engine as possible.

2009 Sorento LX, 4x4, V6, Auto, Red