The only thing I can thing of that will cause a shake like that is oil on the clutch disk. You say you replaced the disk. Did you replace the pressure plate and resurface the flywheel?

Since you replaced the slave cylinder can we assume that it was leaking and that was a source of the oil. If that wasn't the source then maybe your rear main seal is leaking.

When isntalling a clutch, the disk, pressure plate and flywheel must be kept clean and free of oil. Even greasy finger prints will cause a problem.

Hope this helps.