Front end noise - Intrepid 99

My 1999 Intrepid has a rather unusual problem (which currently has
72,000 miles on the odometer) that has been bothering me since I
bought it a year ago. It was intermittent but now its more often than
not. There seems to be an odd clacking noise in the front end, and I
can't figure out what's been causing it.
The clacking sound usually occurs (on the passenger's side I suppose)
when I hit bumps or dips on the road regardless of speed but recently
I started hearing it while driving in a straight street at 30 mph. It
is the same clacking noise but a prolonged one. It looks like a loosen
part hitting another.
I've had two mechanics look at this problem since March, and neither
of them could find anything wrong (the noise went away at the
inspection times). Both of them said that the suspension components
seem to be tight and in good order.
I'm stumped as to what may be causing this noise. If I have my car
jacked up what should I look at? Can I figure out what the problem is
by simply touching the front end parts?
I'd also like to know -- is this normal for the car's old age, or is
it a sign of a major failure waiting to happen?