[Biturbos4] Accelerating "thud"

[Aurangzeb M. Agha]

Posting to this list about problems w/ my '01 S4 is getting tiring.  It 
seems that shortly after I broke 100K miles (now at 102.5k), its started 
to go down-hill and there seems to be something every couple of weeks. 
Anyone else see anything similar?

On a drive to Boston on Sunday, I noted that as I got over 45 MPH, I 
started to both hear AND feel a consistant "thud thud thud" coming from 
the (front?) of the car.  The sound only sped d up as I accelerated and 
slowed down as I decelerated.

I stoped to check all four of the tires to make sure there was nothing 
stuck on them causing the sound and minor vibration, and took it into my 
mechanic yesterday.  He drove it and said he noticed it, but couldn't tell 
what it was.  He balanced the front wheels for me, but afterwards, I felt 
the same thing--no improvement.

Boston's roads are notoriously bad in terms of condition--massive 
pot-holes, etc.  I've scheduled an alignment for this Saturday morning, 
however I'm pessimistic this will help much, as on the highway, the car 
drives in a straight line at 65 MPH w/o me touching the wheel.

Anyone have any idea what this might be due to??

Thanks in Advance,

Aurangzeb
--
'01 Silver S4