Sticking Thermostat?

I have had my 04 Cruiser for 13 years. It now has
200,000+ miles on it. Recently had a bunch of work
on it (Thermostat x2, thermostat housing, coolant
sensor, valve cover & gasket, exhaust manifold
replaced) Fan comes on properly. System has been
pressure checked. No leaks of any kind. Only
remaining issue? Within the first 10 minutes of
driving (1st drive of the day), the thermostat sticks
& goes almost to the red zone. After turning off the
vehicle & waiting for a few minutes, it goes back
onto normal operating range & runs like a champ
all day. Frustrating and really wish we knew what is
it could be. Any ideas?