I changed the clutch master cylinder and the clutch slave cylinder on my 97 sidekick and I still have no pedal

Try bleed

1. Check the fluid level in the master cylinder. ...
2. Locate the bleed screw on the slave cylinder. ...
3. Attach the hose to the bleed screw. ...
4. Open the bleed screw on the slave cylinder. ...
5. Have a friend press the clutch pedal in and hold it. ...
6. Close the bleed screw. ...
7. Have your friend release the clutch pedal.

Bleeding Clutch by Blocking the Slave Cylinder

Not sure if I understand your question. Sounds like the push rod from the clutch master cylinder is pushing the cylinder off the firewall. If that is the case it could be that your rod wasnt fully engage into your cylinder make the rod to long and with enough pressure is popping the clip off the fire wall

Check the hydraulic clutch operation. This is a clutch master cylinder with a reservoir on the firewall, and a clutch slave cylinder down on the bell housing of the transmission, with a steel tube running from the master to the slave cylinder. When clutch pedal is depressed, hydraulic fluid (brake fluid) is forced from the master to the slave. The slave cylinder should push out a little plunger that contacts the clutch fork lever-pushing it forward to engage the clutch.
Add brake fluid to the reservoir if needed. Watch the plunger on the slave cylinder: if it moves little, or not enough, try bleeding the slave from the bleeder valve. They are bled just like brakes. If bleeding doesn't help, your clutch master or the slave may need replacing. The master cylinder, like a brake master, has internal seals that hold hydraulic pressure, so force can be applied to the plunger on the slave cylinder.

check the clutch master cylinder to be sure it has fluid in it... then check the clutch slave cylinder to be sure it is moving freely.

Thn the problem is the clutch master cylinder, it should build up pressure, ok try out this, remove the pipe which is going to the slave cylinder either from the clutch master cylinder or at the clutch slave cylinder and get someone to pump the pedal while you block the pipe and see if there is fluid thrown out with pressure.If there is pressure there thn fit back the pipe and refill the reserviour wth brake fluid and open the bleeding nipple at the slave cylinder let some fluid pour out and tighten it and thn pump the pedal and retry bleeding.
If there is no pressure at the pipe thn its the clutch master cylinder.
Hope this helps!

more than likely the slave cylnder in the tranny or on the side of the tranny have you been seeing fluid on the ground.

Replace both clutch slave and master cylinders, and bleed well. I've also had this happen.

You may have a worn out clutch master cylinder. Check if there's fluid leak at the rear portion of the cylinder.

did you bleed the air out of the slave cylinder. Do this by having a buddy sit in the car pump this pedal a couple of time and then hold it to the floor then open the bleeder valve on the slave cylinder. repeat until just fluid comes of or the bleeder valve. refill slave to proper level with recommend brake fluid. hope this helps.

You could have either a failing master or slave cylinder or the hydraulic fluid level is very low which could also be from a leaking master or slave cylinder; check for wet-looking areas around both.
The master is located either inside or under the hood on the firewall; the slave is located on the transmission housing itself.
Until you locate the problem, use neutral gear position when starting so the tranny doesn't drag and load the starter.
After replacing the defective cylinder, be sure to bleed the lines (like when doing brake repairs) to avoid having an ineffective or just spongy pedal again.