Shaking & Vibes from clutch?

[Joopin]

4.0 '91 YJ with an AX-15...
A few weeks back I noticed a vibe which I thought was a U-joint. I changed it, wasn't the prob. Since then I have figured out how to stop the vibrations by workin' the clutch pedal. It gets the shakes when in 3rd 4th and 5th, if I push the clutch down half way when its vibrating then release, the vibes go away.

It also vibes sometimes when idling, but goes away when I push in the clutch. It also comes and goes whenever it wants when I'm driving.

I have never done any clutch work before, so I'm not sure if this is a sign of it needing replacing. The pedal has lost a little height. Any ideas? thanks.
Joop

 

[TwistedCU]

Usually a clutch showing wear would start engaging higher up on it's range of movement, then as it gets worse it will start slipping.

My guess is it's probably still a U joint or other part of the drivetrain. You're just taking some of the stress off it when you disengage the clutch.

 

[Joopin]

Well the local driveshaft guy didn't find anything wrong with the driveline, he didn't even feel the vibes that I said were there. That's how random this thing is.

 

[TwistedCU]

If you dump the clutch, or maybe just launch a little harder than usual does the clutch slip at all?