I had a similar problem a year ago.
The engine will race to 3k rpm at random and sometime stalls afterwards.
Eventually I notice the temp. gauge would go down to zero before it stalls.
Maybe the ECU can not handle this kind of change, try to compensate and caused the car to stall. I had the thermostat changed and knock on wood so far so good.

I've searched the archive here on stalling. A lot of it attributed it to a intermitten fuel pump relay which you can temporarily rig it so that it is always on for testing. If the problem goes away, that's what you should replace. Some other solution I read included battery replacement, battery cable replacement, cleaning electrical contact.

Hope this helps.