I have a 1996 'N' Reg A8 3.7 Sport Tiptronic.
When changing back down the gears i am getting a thump as if it is struggling to change from 3rd down to 2nd etc. However, if you switch over to tiptronic and change manually it is perfect !
So far i have had it scanned with a diagnosis machine and all it came back with was 'Throttle Position Sensor Out Of Range'. After talking to a few garages i was told this could be the cause of the fault, therefore i went ahead and had it changed, once fitted it was checked on computer again to ensure it was producing the correct values and it all looked ok, HOWEVER, after a short road test, it was clear that the fault was still present.
The car was then put back on diagnosis and no faults were found.
Both myself and the mechanic who has been working on the car have noticed that the fault only seems to occur when the engine is warm, it never happens within the first 10 - 15 minutes of driving.
Does anybody have any suggestions ???

 

It may be worn-out transmission mounts...

Try another transmission program through vag-com..