Actually when you talk about overheat. It does overshoot to about 100 deg before falling back down to normal 80-85 deg.
It has been doing this for a long time (2 years). I changed the thermostat and flush the radiator a few times with different people but nothing works so far. I have given up.
For the smoke, it is dense white and I relly think it is coolant because the coolant level will go down significantly after these white smoke problem occurs.
The car also gives a bit of black smoke under full accelaration (5000-6000 rev).
I love the car and really want to keep it. I hope all these problem can go away soon.