1996 transmission 3rd gear wont shift at times

I have a 1996 windstar with 97,000 miles on it. Last Sunday drove 200 miles to Poconos Mountains, no problem... Next day drove around in morning, then headed back home and after driving 65 miles an hour on interstate for 25 miles the rpms shot up back and forth for about 5 minutes.... I think was loosing my gear..... It settle down and was okay and I drove for about another 25 miles at 60 mph and I slowed down to pay toll the rpms shot up and stayed there... I drove home at 45-50 mph at around 4000 rpms for about 40 miles ( With no 3rd gear).... Stopped and checked fluid and level was okay and the fluid was a little brown... I even stopped at a auto store and put some Lucas anti slip fluid in it....
Came home and parked the van for an hour and started it up and drove it and there was no problem with it.... The van worked fine until Thursday and it started acting up again.... It works sometimes and sometimes not.....I'm not sure if it is temp related or not.... I know when its cold it seems fine....
Changed the fluid and filter yesterday..... Drove the van about 10 miles and it acted up again....
I have read where some people say about changing the TRS..... Is that what I should do? I have no check engine light...
Let me know what I should do..... Should I add anything to the fluid.... Take it to the dealer, even though I don't like that idea...
Thanks Wayne

Hi, RE, Your 96 windstar shift problem, Your symptoms are just one of many that can be caused by the TR, trans range sensor, The TR can cause this to happen without setting a code, ... Just to be sure, Stop at your local ford dealer, give them your vin# and have them check for TSB'S on your problem, This should be a freebee, ......GOOD LUCK.....Clay.

hello, i am having the same problem with my 95 Ford Windstar. It just started within the last month or so. I have noticed that if i am on the road for any length of time it will start acting up, not shifting from second to third, running at speeds of 60-65 the tachometer will jump up to 4000 rpms or higher, as if the transmission has jumped back into second at higher rates of speed. Tonight it has gotten to the point of driving at 40-45 mph without much improvement in the problem. I just purchased the van last fall and have already had to have the freeze plugs replaced a month ago at a cost of $600.....any suggestions on where to start and what to ask my mechanic to check for?

stressed out

Hi, Stressd out, Please read my response to greenman; The TRS, Trans range sensor may be the problem, Also check the white connector on the TOP of the trans bell houseing, Unplug it and check to see if the connector pins in the male and female ends are green or corroded, Lots of moisture problems at this connector, If you choose to get a TR sensor, BUY OEM from the dealer, there are updates on the sensor to solve these problems, The dealer will need your engine size and trans ID, which is on a white tag on top of the trans.......GOOD LUCK....Clay...