I've posted before about this issue and have improved it over the years by fixing things that contributed to the issue (leaky injectors for one).

But I haven't completely solved the problem. It's very specific. Wondering if anyone else has experienced this and knows what it is?

Car starts up just fine (even though it was parked for 11 months! Started right up!)

Drives just fine around town.

Get on the highway and go on a road trip... Couple hours in, pull over into a rest area, leave car idling, have a sandwich, let dog pee, get back in car, slowly leave the parking area, engine bucks and stalls.

Restart the engine and it's good to go no issues.

Rinse and repeat.

Something about idling after a prolonged highway drive causes it to stall under low rpm-low throttle.

But restarting the car solves the issue.

My running theory is MAF sensor misreading, and restarting the engine is reverting to using the ECU's tables instead of MAF reading. But I thought that only happened on cold engines, not just a restart.

I've also got a persistent O2 sensor "out of range, too high" engine code on the pre-cat O2 sensor. It's been replaced twice, so it's not the sensor. Wondering if that is confirming the MAF being bad.

But that's just a guess. Does anyone have any other theories to explore?

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2006 BMW X5, 3.0i - 161,000 miles
2003 Ford Mustang GT - because having Two cars that keep dying seemed more exciting.