98 Windstar Transmission Quit while driving

While my wife was driving our 3.8L 98 windstar the transmission started to slip. Now we can only drive it in first, as soon as its out of first, it starts to slip. it can only be driven in first gear at approx 20kmh. it works in reverse. Does this mean my transmission is done for?

any tips would be appreciated!

Unfortunately, the only way to know is to take it to a good mechanic for a proper diagnosis.
It does sound like trouble beyond what a simple fluid change can do.
The fact that is shifting....and slipping indicates that it might be more serious than a Transmission Range Sensor.....aka neutral safety switch.
A diagnosis will include checking the codes.....which should help in determination of what is wrong.
There is a chance that you will be able to pull some codes with a generic OBDII scanner.....so getting ahold of one and pulling the codes might be a good idea....most likely, you know someone who owns a scanner that you can use.
There are a number of transmission related codes in the OBDII "P" codes.
If a Autozone or other auto part store that checks codesis super close.....you could have them read the codes....but you should not drive the vehicle very far in this condition.

There are additional transmission codes that require a more advanced reader....that will only be found at a shop (as they cost thousands of dollars).
With this equipment, they can do a much more in depth diagnosis.
Also.....when they drop the pan......and look at what is there....they can get some more information.

I had the exact same thing happen in my 98 Windstar. It turned out that after the van would heat up, it would slip into first gear and that was it. I took it to a transmission shop and it turned out to be Transmission Range Sensor was bad. They told me this is a common problem in the 98 Windstars. The cost for the parts and labor $130.

Your Windstar is sensing a problem in the transmission and is defaulting to what is called the "limp home mode". With my '98 the torque converter self-destructed and didn't post any codes that neither a transmission shop nor a Ford dealer could detect.

The range of codes sent by the transmission is rather small as most codes on most cars deal with emissions related items instead of mechanical items. Mechanical problems are deduced by understanding how those systems affect the readings of various emissions sensors.

If no codes show up you'll have to pull the pan and take a look. Hopefully yours is a smaller, rather than larger, problem.

Good luck,
Brent