Stalling after extended (usually 90 minutes or more)highway driving in hot weather. Only happens in hot weather. Turning off the AC doesn’t eliminate the problem. Letting the engine cool down for an hour usually fixes the problem.
Most likely something in the ignition circuit is failing at high temperature, such as the ignition coil or ignition module.
May also be vapor lock in the gas line.
I strongly doubt it would be vapor lock, unless you got an ultra-rare carbureted Mountaineer. Is the Check Engine light on? If so, have the codes scanned (done for free @ a lot of auto parts stores). This will likely get you pointed in the right direction - I’d suspect an electrical component heating up and failing - ignition, as mentioned before, or perhaps something like a fuel pump relay.