We are currently having the same problem with our jeep. Your post has been very full of helpful information (sorry you had to go through so much trouble). The trans relay that was shorting out that finally fixed the problem when it was replaced, is it located in the fuses or under the steering column or where the spare was? I thought if we start with it, we may save some money trying to fix the problem. It acts like it is a short with an electrical item.