[Accc1987]

I'm wondering if anyone has had this. Checked my coolant temp with icarsoft reader and within the hidden menu. The readings I got were up to 90degrees when stationary and fluctuating between 70-79 when moving this included the temp gauge inside car going from the middle back down a notch and back up ect . More towards 70 when Doing 70/80mph. I decided to change the main thermostat on engine and replaced coolant. Thought all was sorted but driving a 60 miles journey today it was the same staying more at 70c I thought this would've sorted this after reading so many posts about them failing.
Any advice would be grateful