Vibration ???

[Solomon Ngan <sngan@netaccess.on.ca>]

Hi,
I have had vibration problem for a while.  Since I replaced the old
tires with Dunlop D60A2, it is much much better.  However, there is
still a vibration anywhere between 100 to 130 kph.  The strange thing is
it comes and goes.  I could set my cruise at 120 kph, it gives me the
shake for a while and then stop by itself.  It doesn't seem to be the
road. I was observing the road condition, at least I don't notice any
major difference.  Just to clarify it, the shake is better better than
before, but something is still there.
Any clue ??
Solomon
'90 90q20v