Judder stationary

Hello,


I am new to this forum and just bought a MY80 928 Manual Euro in moccabraun with
It is very original and very very nice
One thing though: When the car is warm and I am at a stoplight (engine speed stationary) the car rocks from left to right pretty badly.
Strangely it doesn't do this when cold (engine speed higher?).
I read a couple of posts about this phenomenon, but I could not find a conclusive story so far.
Can anyone help me out as to what this can be?
Much appreciated.


Regards,


Vincent

Have you checked the engine idle speed while warm? The specs are:

idle speed setting: 700 RPM plus/minus 50

These are tune up items:

Spark Timing: 28 BTDC @ 3000 RPM (vacuum hose detached)

CO% 1.5% plus minus 0.5