spouse's '92 965 with '96 engine installed last year. she's on the interstate, doing about 70 mph in the left lane, when the engine shuts down with no warning. Steering apparently still working long enough to guide it to to right-hand breakdown lane through the traffic, then all the idiot lights come on, and engine will not start. Ambient temperature about 95F, ambient humidity about 60%. Plenty of fuel, and the engine heat gauge never moves from the center. I get there about an hour later, pick here up from the restaurant where a kindly state trooper has taken her, and we go back to secure the car for towing. It starts, and runs fine for the hundred miles to get home!
She commutes about 35 miles each way on an interestate with a lot of stops and slow-downs for construction, in summer temps approaching 100F , so I don't want this to happen to her again.
Anybody have a clue? The only thing like this I have seen before was on a '74 144 which once did damn' near the same thing on a 100+ degree day--went down about every 20 miles, with a wait of up to an hour before starting each time. Never did figure it out, but it sure as hell looked like what we dinosaurs called a heat-related vapor lock.

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We have met the enemy and they is us. [Pogo] S70 T5 cop car : Rough Rider suspension, Walmart fog lights, eBay speakers, ambiance by Pall Mall, trim by Le Duc d'Tape, 8-channel THD by OEM amps