Transmission glitches on 1998 3.8L Windstar

Hi!
There are at least 4 threads on this forum describing Windstars with the following transmission symptoms: 1) harsh 1>2 shifts that occur only when fully warmed up; 2) the harsh shifting immediately disappears if the vehicle is restarted; 3) presence of P1477 torque converter service engine code. Unfortunately none of the posts had a followup describing the root cause and repairs.
I'm now in the same situation with my '98 GL 3.8L with 180k. The transmission fluid is due to be changed and I'm wondering whether to do that and/or replace the Transmission Range Sensor (since it is inexpensive) or just put those dollars toward a transmission rebuild or new(er) van???
Thanks in advance for your help! I have enjoyed reading the threads in this forum!
- Rumbleseat

I would change the fluid.
I recommend a high quality synthetic fluid that meets the Mercon V specification.
Make SURE to fully fill the fluid to the FULL mark on the dip stick....measured with the vehicle warmed up, on level ground, in PARK and the engine running at normal idle.
Even very slightly low fluid can cause issues.
The Transmission Range Sensor is a relatively inexpensive repair that is common.

I'd probably drop the pan and change the filter too if you've never done it. That's one thing I just paid a local transmission shop to do for me. For $169, they exchanged ALL the fluid with synthetic (via fluid exchanger, flushing out everything including the torque converter), put in a new filter, and even showed me the 'contents' of the pan and magnet (to satisfy my curiosity) before running it through a parts washer. I hate dropping these pans with no drain bolt, so it was nice to let some else do something for me for a change.

The contents of the pan (amount of metal on the magnet, etc.) can give you a feel for how much life the transmission has left in it.