There have been a number of modifications to this engine involving software, spark plugs, camshafts, injectors......

A bit of a dog unfortunately, take it to a dealer or AL VAG equipped workshop to start with a software check, there is a relevant software update for reported misfires without a customer complaint on certain software versions. If it's in need of an update this is a starting point on this engine, it may have deeper issues in need of a wallet check on the customer.