Ford Expedition goes up to 20 mph. Then engine revs faster and rpm jumps, but car won't go faster. I turn Overdrive off, and the issue is gone. What's wrong?

Check the transmission fluid level but things don't look good for your transmission. If you need a new one I highly recommend buying a Ford factory rebuilt one.

You don't say how many miles are on the Expo. Sounds like OD is slipping. As above, might be just fluid low if your lucky.

It has 190k. The transmission was rebuilt about 100k miles ago.

The transmission fluid seems fine.

From what you have said, I believe your OD is slap worn out and needs to be replaced.

Thanks. Do you think If I drive it with overdrive off, Is there a risk the whole transmission goes?

Drive it? Maybe to the repair shop if it's not too far.

The OD is an integral part of the transmission. If you drive it and it lets go, it will take the whole transmission with it.

OD off means that you are now only using 123 gears. Your tranny should be a 4speed and shift to a higher gear with OD off !

DID you ever figure out what was wrong with it? Im experiencing the same issues

My truck is doing the same thing We just replaced transmission and still same issues

I’m having the same issues with my Ford Expedition someone told me my transmission is burnt out

I believe it could be the overdrive servo, the retaining clip has a reputation for being brittle and falling apart in this trans... there are some great videos on youtube that can show you how to rebuild that particular part of the transmission in great detail