I'm not a mechanic so don't pin me on correct terminology guys
A friend of mine (who IS a mechanic) works for various dealerships, including some Ford dealerships. On of them also had an Explorer PHEV ST line with vibration issues.
They changed the transmission, driveshaft, diff and what i believe is called the "transfer case". That finally fixed the issue.
They suggested that it would be easy to test this fix by unplugging the harness from the transfer case and drive it like that.
This causes a myriad of issues like esc, abs, tc, brake assist, auto hold etc to fail but you CAN drive the car like this. (Quite fun actually in the wet haha, easy burnouts
)
So i discussed it with my dealership and they unplugged the transfer case, essentially turning it "off".
This made a world of difference!! I didnt even realize how bad the vibrations actually were until now! Even at other speeds the car is quieter and the wheel is completely still!
Under full acceleration i can notice a vibration on various speeds, but besides that it's completely gone. Even at the 100mph mark. My guess is that the power output still has to "travel" through the transfercase and under full load its just not keeping up as its still a defective unit in my mind.
Fingers crossed, replacing it with a proper transfer case will fix the issues completely.
Ill keep you guys updated as this process continues.