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It sounds as if you may have a powertrain control module issue, an alternator putting out AC current, a vehicle network communication problem between modules, and/ or electrical interference in the vehicle speed sensor circuit.
If there are any add-on accessories on the car, such as a cell phone, stereo, amplifier, alarm system, or anything else that was not there when the car was built, try disconnecting them to see if the symptoms go away. If not, then you will probably need to take the vehicle in to a technician for evalastion, as none of the other possibilities can be accurately checked without having access to some test equipment such as a Ford NGS scan tool, oscilloscope, and wiring schematics.
It is getting close, but perhaps it is still under warranty?