Yes you really need to check all of those control arms well and they can be
a little tricky to check too! ;-)
The steering rack would show its looseness easier I would think.
Here they discuss the control arm issues..
http://www.passatworld.com/forums/archive/index.php/t-84952.html
from Buster 06-21-2002, 03:00 AM
"I have this problem, but have been unable to get a dealer to properly
diagnose it. In the meantime, I have: floating/wandering at freeway speeds,
increasing difficulty with handling the car, creaking and clunking. I called
another dealer (other than the one that told me there's no problem, and who
I seriously doubt even looked at it), and that dealer wants to charge me
$250 just to look at it. He also said "control arms NEVER fail on these
cars," so I don't think I'm going to spend any $$ to take the car to him!"
CONTROL ARM KIT PROBABLY NEEDED!!!
Excellent brand recommended, and there are many brands out there so please
be careful with your choice! I am trying to research these brands some.
I need to do all of my control arms too, since I have replaced the Front
Lower Left Rear and need the Front Right Upper Front one now! :-(

Signature
later,
dave
(One out of many daves)
1997 Red A4 1.8tq auto
>> After 156k miles the car has developed creaking, clunking, some shimmy
>> and some "wandering".
[quoted text clipped - 13 lines]
> rack. I have seen rack mounting bolts loosen up can cause clunking but it
> is rare.