Engine dies when heat soaked

[Jean-François Roldan]

I have the same problem. This morning it happened twice, and then it restarted but with a highly hesitant RPM bouncing around between 3000 and 5000 RPM non stop while driving making for a bumpy drive, but at least it didn't die again. Drove like that for half an hour or so and it got better (less RPM bouncing) until we got to destination (120 miles). 
Drove again about 20 miles with only a few bounces. 
 
Nothing on the way back, perfect driving condition...
Sounds like the engine speed sensor, the mechanic pulled the code yesterday, but the sensor was replaced about 3 months ago, as well as the crank position sensor. For 2 months I had no problem at all and then it came back a few days ago.
 
Happens when the car is already warm can be while driving or idling. It just dies, RPM goes flat and no restart until the engine cools off by opening the hood. I never had the bouncing problem last so long though.
 
Is there something else that the sensor itself that could trigger a code or this kind of problem?
 
Any idea why at some point it stops dying and drives fine for the rest of the day??? I hate intermittent problems...
 
 
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