Help!! Clutch noise.

84 audi 4000s. 5 speed , 4 cylinder. 117,000 miles. Started making a a shrill warbling/loud "chirping" noise some time ago (at first thought it was a slipping belt as it sounded almost like that but have ruled out belts , AC compressor , all the "ususal suspects") Seems to come and go at will but depressing clutch pedal all or part way makes it change a lot in tone. Seems a little more frequent in city, stop/go traffic)Tried adjusting clutch free play and that seemed to take care of it for a few hundred miles. Noise back today. Does this sound like a throw out bearing? Pilot bearing? I would have thought throw- out would only be noisy while clutch depressed. Don't know if a worn pilot even makes noise. This is constant when it occurs. Once I get up to interstate speed it gradually subsides. Clutch is a little more "juddery" too than I seem to recall it being. (it is car I just got back from my son). Ideas??

throw out bearing,try undoing cable completely and pulling clutch arm away from clutch,does the noise go?if not cable,release from slave cylinder.