re. Cornering feeling *unsafe* 1990 Coupe

[Swann, Benjamin R. (BSWANN)]

This sounds like the symptome I had when the rear lower ball joint was in
process of disentegrating on my 4000Q.  It was hard to find, until one day
the thing came apart completely.  You really have to put a lot of force on
it to see it separating, which is what happens when you are going 'round the
corner.

[Over the last few days I've noticed a certain uneasyness in cornering
in my 1990 Coupe (no Quattro) - the steering seems to be very, very
light and it literally does feel as if on every bend that the rear-end
is going to swing out.
:
:
So, my question is - what caused the car to do this? I do concede that
I may have been travelling a little faster than would be recommended
for the corner - but I've never had the car 'feel' the way it does
now. It really doesn't 'feel' safe at the moment.

Even when negotiating roundabouts and 90deg corners at low speeds (sub
20mph) it still feels very very loose and uncertain.
:
:
Anyone got any ideas what could be wrong before I get onto my local
dealer for an expensive service?]