Hello, here a bit of history.
My 97 had same problem , 3k for rebuilding transmission. 800 for auto electrical to state its not electrical.
5000 km later same ****.
Im going to another auto sparky as closer than original, I will replace all sensors and see how it goes, from there, if no electrical faults fix it, time for another trans flush.
Im in too deep to stop now.
Does anybody recall the name of the place that does the solenoid upgrade packs?