get a voltmeter and test the output of the alternator, should be above 13V if not check terminals and earth are nice and clean, rev engine and see if voltage increases, should be no more than 14.4V if so i'd replace bushes etc, as for idling, try bridging the idle control stabiliser, situated behind bulk head inside engine bay (RHS), the plugs are designed to be mated together for adjustments, this should reduce idle to about 850-900RPM if not i'd suggest replacing stabiliser, have fun!!! if all else fails you could give your car to me and i'll look after it!!!!!!!!!!!!!!