This isn't likely an electrical problem. Chrysler developed the first computer-controlled transmission for the '89 model year, and no one else copied the design for quite a few years after that. You are going to have a normal hydraulically-controlled transmission, and based on your description of the symptoms, (you weren't clear if the car was moving at highway speed or it was standing still and you were somehow expecting it to shift to various forward gears), I would be more inclined to suspect varnish buildup on some of the valves in the transmission's valve body. That is partly the result of the high mileage, as in the case of my minivan, it is aggravated by lack of maintenance, again, as in the case of my minivan, and can first come to light when doing a procedure that runs those valves into areas where normal driving hasn't placed them in a long time, ... As in the case of my van.
For my van, I hadn't hit wide-open-throttle in perhaps more than ten years until one night I was experimenting with the cruise control system, and a test suddenly tugged the throttle wide open for a few seconds. Right after that the transmission developed a severe case of long-delayed up-shifts, and sticking in higher gears when slowing down. I figured out the throttle valve was sticking in varnish buildup that accumulated where I hadn't been causing it to run for many years. (The throttle valve determines, in part, when a shift should occur based on how much load you have the engine under. Road speed is the opposing factor).
My reason for sharing that sad story is to explain how this might be a simple problem brought to a head by your performing procedures that are not common, but you'll need the advice of a transmission specialist to know for sure. Given the series of events, this is not likely to be due to a mechanical problem. There are chemical additives that dissolve varnish buildup but I don't know how well they work.
Tuesday, July 28th, 2015 AT 10:24 PM