Hi all, long time lurker and finally poster.
Lately my 2001 V6 started having some "hunting" between overdrive and 3rd gear when cruising at partial throttle. Then shifting became uncertain WOT, particularly in low gears.
No codes were thrown out, AT has always been serviced but I thought I was facing a major fault; the search for symptoms on this site and on the internet luckily pointed me towards another culprit, the TPS. Sending garbaged signals to the ECU would produce the same symptoms I was experiencing.
So I thought I'd give a look to the TPS for dirt/wear, but those "drive by wire" throttle bodies aren't serviceable except for the MAP sensor (as many members know). And I couldn't find anywhere any internal view showing components, so even the type of sensor was totally unknown (potentiometer, encoder, whatever).
But four aluminun rivets are easily drilled away

First I started with the bigger of the two plates, as showed in the first three pics.
An all metal gearing assembly and a serviceable motor... On the left the throttle gear bottomed out, main gear on the center and motor on the right. All components looked in perfect shape, no trace of wear of any kind. Just a little amount of dry grease that I removed and replaced with a suitable one (i.e. all purpose grease, it's a simple gearing in the end). The plate holds a spiral spring that makes the butterfly closing; upon reassembling, it has to be turned counterclockwise once engaged on butterfly shaft before lowering the plate.

Then I opened the second plate, remaning pics are all about that part and the TPS housed inside.
As you can see, it looks like some sort of potentiometer in a customized case; it holds motor power connectors and potenziometer pins. Unscrewing the two bolts and removing the motor connector will detach completely the TPS. At this point I felt brave enough to cut the melted plastic and reveal the internals: a couple of arms, a couple of spacers and (finally) the tracks. They looked half way between worn and simply dirty, so I took some isopropyl alcohol and carefully cleaned both tracks and arms tips. Tracks are printed on some kind of flat cable soldered to connector pins, better than a traditional potentiomer but still prone to wear and break.
The last pic shows tracks after cleaning, they matted out: a good sign.

Once cleaned the tracks, I started to reassemble the thing; sorry, no pic this time. I was in a little hurry. I glued the potentiometer cover and put the assembly back in. I didn't use rivets, this time; had a bunch of inox screws, nuts and washers (maybe I'll take a pic of the new look, lol). The blind holes on throttle body were threaded (M4), since I couldn't use nuts.
Fitted back the throttle body, reconnected all cables and battery and finally cranked up engine: no MIL, throttle was responsive. Put in drive, let the engine warm up and... WOT! 1st to 2nd was fine, 2nd to 3rd very good as the remaining. Then I reached my normal cruising speed, holding gas pedal. No more hunting! It seems that sometimes bravery pays back

A couple of notes.
In my case the procedure worked because tracks were more dirty than worn out; a mix between carbon debris (from track surface) and metal particles (arms heads). If tracks happen to be severely damaged maybe the only thing to try could be placing another spacer on the bottom one; arms would hit a portion of undamaged track and probably work. Repainting or recoating would for sure alter potentiometer value, so it's up to ECU tolerance coded parameters I think... A hit or miss maybe.
The next is more a personal thought than a note; I really don't understand (if not for profitable spare market) why NONE of the parts is available alone... It would be so damn easy to replace everything in that throttle body, it's all bolted on the inside! And considering that I didn't even run a relearn procedure (idle setting or whatever it does), it sounds really like a bad (sad) joke.

Feel free to ask and improve this writing (not my native language).
Hope this helps someone else in not wrecking those lovely cars for the insane costs of some spares...