Have you had any luck finding out the issue. Our car a 2002 A4 Automatic. When we sit at a light in drive the car shakes very badly. When we put it into neutral the shaking goes away. Audi Canada could not find anything and Also had the torque converter testing and it was fine.
Try dumping some fuel cleaner in the fuel tank. Your dealer will have some good stuff but I would try some SeaFoam. I am thinking that maybe the fuel injectors are not spraying that well or there is excess carbon in the engine. If there is debris on the intake valves, it could absorb some of the fuel before it gets into the combustion chamber. There are faster ways to clean things up too, but you don't want to create problems with your 02 sensors or catalytic converter. JMHO ;)
if what you describe the dealer cannot feel, see or hear then we stand very little chance.....
me I would have hinted, engine mount(s), timing, out of balance something..........
MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.