Mos1975,
Clutch release lever, thats the lever that pushes the clutch bearing against the diaphragm spring, correct?
Assuming correct parts, installation, no other surprises, no previous release system modifications from a previous repair and no contamination of the clutch during the replacement of the release lever, one idea to double check. Can you compress the slave cylinder with your hand while it is still installed?
The hydraulic system is at zero pressure when your foot is not on the clutch pedal. You should be able to compress the slave cylinder and this merely pushes the fluid back into the system and into the reservoir. If you cannot compress the slave cylinder, then it is as if your foot is on the clutch pedal while driving. How it might happen, not sure but it is fairly easy to check, transaxle stays in for this evaluation.
I'll admit, a bit of a long shot, but worth checking.
Good luck,
Gary