if this is your problem then you either have has collapsed top mount (most likely) or the slotted nut is not done up enough to hold the shock altogether. I'd change the top mount first and whilst its off, checked the slotted nut is all the way down (you'll need spring compressors to do this) One other thing, if you change the top mounts, buy a pair of them, chances are if one has gone the other wont be far behind.
