98 trans issue

I have a 1998 windstar and have a problem with the transmission. I was happily going along and went to accelerate up a hill lightly, resulting in a sharp jerk - this was after about 15 mi. of driving the other evening. It drove normally for another mile or so, then did it again, thus I pulled off the road. I checked the trans fluid and it looked fine (not burnt/full of metallic particles), so I started the van again. However, it would not go into any gear, be it R, O/D, 2 or 1, and lightly pressing on the gas would result in a clunk. It was on level ground, so I'm not sure if it was going into N or not. However, after a minute of sitting there with the gearshift in N, trying to figure out how far I'd have to go to get to a phone (out in the foothills - no cell service) to get a tow back home, the car wants to move. I managed to drive it home (w/ perfect behavior even) w/ the gear selector in N, but if I tried to put it in O/D, it would do the jerking again. Needless to say, I left it in N and drove it home and parked it.

I read the codes, and there were none in memory, so I pulled the MAF to see if my code reader was working (it was). It still was having this same issue the next day, except when I would go to start it (in park) it started, then the revs dropped down immediately, like if I had dropped it into gear (rather than staying up a bit for warm-up in Park). Additionally, the motor doesn't rev freely like it normally would in P (very little throttle = 2Krpm normally - now it is like if you were trying to brake-torque the car, but it is in park).

This led me to suspect the trans range sensor / neutral safety switch ( DTR / TR sensor ), per other posts here and on the old cartrackers forum, so I replaced that with one from advance auto ($25). The no going into gear/clunking remains, although it did go into the same mode as before (driving semi-ok, no kickdowns, starting in 2nd) at one point.

What else should I look at before going for the rebuild? It's been about 15k since the last trans fluid/filter change (has 81k on it now), but other than that I'm a bit at a loss.

Do the "scribe" marks on the new switch housing line-up as they should?

Do the "scribe" marks on the new switch housing line-up as they should?
I believe so - the line on the black part w/ N (neutral) lines up with the line on the white part when the trans is in neutral. I will check this again, however.

EDIT:
It is correct - I just checked it. Car started in N ok and revs freely, but anything else (including park) just sits there w/ a load on the engine but goes nowhere - I did not try to move it forward, much, however, as I don't have anyone to help me put it back in the spot if R doesn't work (which it wasn't)

I had sharp jerks at certain RPM, at certain loads. It was NOT the tranny, but an engine miss. I felt like a bump in the road, but from in front, not in my fanny. You would think you had hit a bird or something (very sharp jerk), and no relation to shifting gears. Sound familiar?
See my explanation under the thread
2000 Windstar Stutter/Shudder Quirk

My 98 had the same problem, but at 67K miles. My mechanic dropped the tranny to replace another part (and since I am mechanically ignorant I don't remember what it was), in hopes of not having to change tranny, but guess what - it needed a new transmission. Research on Ford svc. bulletins revealed that this tranny is the same one they put in their Taurus and it is a known dog - especially if you have the 3.8 engine. Good luck, hope yours turns out cheaper than mine!