98 Transmission shifting issue

I just bought a 98 Ford Windstar 3.8L knowing it had a tranny issue. The main problem is that it does not up-shift to higher gears. Here's the details.

1. Reverse, 1, and 2 seem to work fine.
2. When in Drive, it will start in 1st and initially shift to 2nd correctly around 10-15 mph. Once it is about ready to shift to 3rd, it either down-shifts to 1st or stays in 2nd. I can't tell which, I just know it won't go above 30 mph very well in drive.
3. Can start in 2, get above 30 mph and shift to Drive and then around 40-45 mph the RPMs get really high again and it won't shift. I don't know if it is in 2nd or 3rd gear once this happens.
4. I have not yet checked to see if the fluid is old, but it does seem to be full. I'm not sure I've checked it properly with the engine on. Will do this soon and post the info.
5. Replaced the TRS with no change.
6. I have no diagnostic code info and am trying to do what I can without them right now.
7. At this point I know zero history of the vehicle.

When first trying things out, I decided to drive it around a long enough to see if warming the transmission fluid helped. When I first did this, eventually it did start shifting correctly, but once it did the OD light started flashing as well. I put in some stop-slip additive and ever since then it has never gotten back to shifting like it did that one time. I have also never seen the OD light flashing again. After this I had changed the TRS (aka Neutral safety switch) with no effect.

I intend to open one of the transmission hoses to the radiator and turn on the engine in Park so that I can check the fluid and confirm I have pressure. I will post the info then.

If I find that I have pressure, good fluid, and still have the issue, then I'm beginning to suspect either solenoids or the torque converter clutch.

Any thoughts?
I could probably do any repairs that don't involve dropping out the tranny.
What possibilities are there that I can try before having to take this to a tranny shop?
Anyone know any good tranny shops in Wichita, KS?

first gear is foreward clutch on,,,,2nd gear is foreward clutch on with element locking gear train,,,,3rd is,,release locking element ,,,apply foreward clutch and direct clutch on,,,,,if trans feels like it falls to first,,,direct clutch is burned ,,,damaged,,broke,,,,......tranny in a can,,,solenoids,,,,,new filters ,,,,clearing codes,,,,changing sensors,,,swearing {some times helps},,,,probably broke......The computer system has a problem with mechanical issues,,,,,when system commands a solenoid on,,,,if shift result is not what it expects,,,,will fault that solenoid even though it is working properly.....If dumping van ,,,find a used one ,,,,,if keeping van rebuilding is best,,,,,ATSG or ATRA affiliated shops will do the best,,,,have aftermarket info to address all engineering problems gbaum

What you describe is the "limp mode" operation......if you are lucky.....it could be the Transmission Range Sensor (TRS) that is mounted on top of the transmission case.
If you are not lucky, it is something more serious.

You might also get lucky and have some "P" codes stored, which any OBDII code reader can read.
Otherwise, you will need to have it diagnosed by a good shop.....which can read the other codes....and perform diagnostics on it.
Even then.....it could be a guessing game as to what is really wrong.
If replacement is needed........When mine went in my '96, I got a FORD remanufactured unit......in 2001'ish.......and it has over 120K miles on it.....still doing well.

Mine did the same thing yours did.......was TRS.....then shortly after that it happened again.......more serious.
If you want to make a guess.......replace TRS (around $50 for part) and verify fluid level and condition.
If that solves the problem.....change the fluid if it has not been done in the past 30K miles using a Mercon V rated fluid.

I've already replaced the TRS and that didn't help. Today I also changed the fluid and the filter and that didn't help either.

I'm debating trying one more thing before taking it to a shop. I've read some about the Vehicle Speed Sensor (VSS). I might replace that if it's not too expensive. If that doesn't work, then I'll concede to take it to the shop. I'll post details once I know more.

Well, I thought I would leave an update. Looks like trannyman52 was on to something. The tranny codes said incorrect gear ratio for gears 3 & 4. They said something in the clutches wasn't working, so it needed a rebuild.

However, some might be interested to know that when I changed my Vehicle Speed Sensor, I had only a little trouble getting to it and changing it WITHOUT removing the exhaust Y-fixture or the side wheel mount. I just had to get the right size ratchet extension at the right angle between the tranny and the engine. Granted I am a small guy and was able to get my hands and arms where bigger guys may not, but I was able to change it out in about an hour.

Thanks for all the help.