Bought a 5 speed blazer and at first I thought I just couldn't figure out how to drive it. But now I think there's something else going on.

My issues are that it "clunks" when I let the clutch out. It's really noticeable and sounds really bad on 1-3rd gears.

I was thinking motor mounts or tranny mounts, but they look ok visually.
Now I just got a clutch code P0704 clutch input circuit malfunction.
so I'm wondering if the symptoms are related. Anybody able to help me out with a diagram? I thought I found one showing that the cruise control and clutch input sensor circuit are intertwined somehow which is interesting because my cruise control doesn't work either.

 

Could it be something in the driveline? Some sort of u-joint, bearing/seal failure? It only does it if I shift fast and let the clutch out fast. If i rev it up and then coast a sec then slowly let out the clutch it doesn't clunk or lurch at all