The driver's side power door lock actuator is a electrical solenoid that is mounted on the actual latch.......the cleaning and lubrication would have been the FIRST thing that I would try.
Seems those TRS modules act up a LOT on the windstars around your vintage.
Also make sure that the fluid level is FULL when checked with the vehicle on level ground, motor running at idle, Gear select in PARK.
Even slightly low transmission fluid level can cause what you are having.
Also, make sure that the fluid has been changed on at least the 30K mile interval.....a cooler line fluid exchange takes just over 12 quarts.