need help with my 90 jetta

I have a 90 jetta with 300,000 miles. recently ive had trouble
starting. In the cold the started sounds funny and I hear a clicking
sound from behind the instrument cluster. Its just takes a while or I
pop the clutch to start it. No problem, until today. The clicking
sound started while I was driving and if i took my foot off the gas
the rpms would instantly bottom out and Id stall. I replaced the
battery cables recently with generic non-vw cables and they didnt fit
exacly right. Could my problems be explained by a bad ground? Also
today my horn started beeping for no reason. Do I have a case of the
electrical gremlins? by the way the clicking sound kind of sounds like
a cuircut breaker "on-off" kind of switching sound rather than a
plastic gear grinding sound. thanks in advance for any help.  btw,
whats the record for most miles on an original clutch?