First thing to check and swap would be the coil packs and spark plugs. The next culprit would be the either the pre- or post-cat exhaust sensors, which are often the cause of engine lights.
There is certainly no need to have the engine stripped - completely unnecessary. If you take it to Audi, they'll almost certainly get to the bottom of things quickly, but it will be costly, in terms of labour alone.
Cheers,
Mike