So Borat, what was this "shaking of the engine" that you solved? what was the problem..an EGT sensor or something else?

i dont know what is in english...but not EGT, and not O2 sensor.

Vag-COM didnt show anything else, but in audi service they change one of two boxes on airbox
(ecu of three valves...i dont know how it say in english)
OEM number of this part is: 4A0 905 351 A

Oh...so it was the ICM, or ignition control module...that makes sense...it is not rare for those to go bad...a weak one will cause intermittent and constant misfires, or engine shaking ..as you called it... well... good for you...im glad you found it...now you can drive and enjoy a S4 with no precats!!

thanx :-) i have precats.....i get out second CAT's (bigger)