1999 Ford F-250 transmission clutch

Can you tell me what it is doing?

Are you sure the slave is properly mounted? What do you mean by "it wont go down?" Is it solid and you can't move it and other times it drops with no pressure?

Tell me, does this sound like your vehicle? Are these the directions you followed? Also, how are you going about bleeding the system? Was it done before the components were installed or in vehicle?

1. Place the slave cylinder on a clean, flat surface
with the bearing facing up. Press down on the bearing
to reveal the retaining ring and two washers located
on the end of the slave cylinder.
Remove and discard the ring and washers.
2. Lift the bearing, spring boot assembly and plastic
spacer off of the slave cylinder.
3. Remove the slave cylinder spring located inside
the boot assembly and set is aside for reuse. Discard
the rubber boot, release bearing and plastic spacer.
4. Seat the new release bearing assembly on the slave
cylinder spring and install the assembly on the
slave cylinder.
5. Press down on the bearing to install the new
retaining pin.
The slave cylinder is now ready for installation.