This problem is pissing me off. In the morning, I start up the car. It gradually heats up, I start driving, and the temp will keep going up, well into the red, and will eventually stutter and drop down to a normal temp. It's fine the rest of the time.

Is this a problem with the t-stat?

 

Sounds like an air pocket gathering right under the thermostat causing a "false" temperature reading. Stat could also be sticky. Try replacing the stat. Could be worthwhile to drill a few small holes in it to allow air the bleed through.