I need some help diagnosing a suspension problem

[Tim Penasack]

1986 4KTQ Rally car - 2 Bennett coil over suspension with Eibach springs and
Koni Yellow strut inserts. (90 URQ rear strut housings with 5K hubs in the
rear and 5k strut housings and hubs in the front)

Problem:  Started happening on the last 2 stages of the Rally New York 3
weeks ago. Traveling at pretty much any speed and going over bumps the rear
end seems to shift suddenly. It is not significant enough to alter the
direction of the car but enough to make you really pay attention. It is hard
to tell a direction.  I dropped the rear sub frame today and found no cracks
or breaks or totally blown out sub frame bushings (they do need to be
replaced though).  Diff seems solid with a little  vertical movement in the
inboard CV cups but nothing that would cause this shift.  At this point I am
thinking it is one of the rear struts - I haven't dropped and disassembled
either of them yet - but I am thinking one of the strut inserts may be bent.

Anybody ever some across this problem?  Any other ideas?

Anybody know what Koni's warranty is on the yellows?

-Tim
I need to get this fixed soon since I have another race at the end of
October

1986 4KTQ - Rally Car
2001 S4