I don't have any solutions, but there is no way.... NO WAY that one door could be "hot" and nothing else. NO WAY.

Wheather static, 12v, or 330v, the car body is all one united piece of metal.
Whatever is on the passenger side, is on the driver side, and is on the tailgate and hood.

There is a 99.99% chance this is static electricity.
Someone should tell the cardiologist that lightning is STATIC ELECTRICTY.
Static electricity refers to the source, not the strength.
While we haven't solved the mystery, at least we are all learning SOMEthing!

Good luck.
-John

P.S. No one has mentioned a shorted spark plug or coil-on-plug in this case.
There's 1000 volts right there, and could be intermittant. What else on this car has capacitance?