I have a 2007 with 2.2l, auto w/278k miles. I notice that as the temperature gets to the higher side over 200 the engine starts to pick up a (miss). The check engine light doesn't come on but there is definitely a different feel about how the engine is running. I have recently noticed also that the dash coolant temp gaugs sometimes climbs to 219 (once I saw 220 for a split second) could the sender unit for the fan be going bad? The fan does kick on but I am afraid for it to get too high and damage things. Any help is highly appreciated.

 

Does the Check Engine Light come on momentarily when you start the car?

You can still check for pending codes.

 

Have you checked the coolant level under the pressure cap and in the bottle? While moving the temp should stay 190-200F, in stop 'n go traffic it might get up to 220F the fan is supposed to come on around 217F.
The engine acts funny because "something is wrong". When the engine gets too hot the computer goes into "defense" mode, it will shut cylinders down in an attempt to cool down.