2000 Renault Scenic engine stop offten in summer

When the stalling condition exists, does the car gradually lose power no matter how you push the throttle until it comes to a stop? While doing this, does it kick or buck a lot? It sounds like a good old fashioned case of "vapor lock". The answers to the above questions will help narrow it down. Please advise.

The over speed protection will usually just warn you of over speed. It won't hold the car back and surely won't stall it. If your talking about "over rev" protection, that will only let you rev up the motor to a certain rpm, but it still won't stall the car.
Why does the car do this only when it's hot out? The hotter the air is outside, the hotter it is under the hood. If you pull 100 degree air through a 200 degree radiator, the underhood air temp is approximately 150 to 175 degrees. 40 degree air through a 200 degree radiator is approximately 90 to 110 degrees.I don't remember at what temp gas boils, but I think it's around 145 degrees. I looked to see if there were any TSB's out on your problem, but Renault isn't in my system. To prove my theory you could insulate the underhood fuel lines and fuel rail with foam rubber or anything suitable and see what happens.