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There is a good chance the fuel pump is failing. Let me know what the pump sounds like. You may be running the pump dry as the fuel sloshes away from the fuel pump. You may even have something loose in the tank causing this when the vehicle goes up hill RT. Not uncommon for a focus to need a fuel pump assembly at 120K, you actually did good to last this long.
I am not saying it could not be a wire shorting to ground in the harness but the pump failing is much more common. Make sure you change the fuel filter too
there was a recall that extended the coverage for the fuel pump for 10 years
lets start here
The fuel pump and the fuel pump relay are both on f9. I would expect the vehicle to lose power/hesitate if the fuel pump quit. since you said it is more like shutting off we need to consider what else is on the circuit.
The MAF sensor and both 02 sensors are on this fuse also. If the fuel pump draws to much it could blow the fuse which would shut down the MAF, that could cause a stall like the vehicle was shut off. You could make sure the MAF sensor and 02 sensor harness show no signs of rubbing. Lets make sure there are no possible shorts on these 3 components.