Update:

I got the car re-alligned and replaced the front right outer cv boot.

The pulling to the left has stopped, but I'm still experiencing an
issue.

I have to grip the steering wheel tightly in order for the car to stay
straight.  If let go of the wheel while driving on the highway, the car
will drift to either side, depending on the pitch of the road and which
lane I'm in. (Left lane = drift left, Right lane = drift right).

I've driven other cars where i could lightly hold the wheel with one
hand and the car would drive straight, but this one does not.

What could this mean?

Thanks,

Joe

It's useless to say anything without an alignment check.

Ronald

I have a 2001 Audi S4 6spd with 92600 miles on it.

Here's the situation:

When I drive in the left lane of the highway at about 80mph, the car
drifts to the left.  When I move to the right lane, it starts to drift
to the right.  I brought it in to the mechanic and they said that the
problem was worn tires.  I brought the car into NTB and got new tires
put on.  Now the problem is worse.

When I'm in the left lane of the highway, the car pulls hard enough
to the left that I have to use constant force to hold the wheel
straight.  To go along with that, while making a right hand turn (on
the highway) I can really feel the car trying to pull to the left.  I
don't get that feeling when making a left hand turn.

I've never experienced this amount of pulling in any other car I've
driven.  I recently had an alignment done before this issue.

When I brought the car nto NTB to get the new tires put on, they told
me I had a bad front right outer CV joint.

Would this be the reason for the pulling to the left?

The steering doesn't feel loose.  It responds well when i turn the
wheel.  When the car pulls to one side, i can definitely feel it in the
wheel.  Does this mean that the power steering is bad?  Or could it be
a control arm?  I really have no idea.  I wouldn't know what to look
for.

I appreciate any advice you can give me.  

Thanks a lot,

Joe