engine light on dashboard , misfire on idle. on 2005 Audi A6 Quattro

my a6 2005 , is running very smoth when driving , but on idle and at starting , I feel cuts, and almost wants to turn off ? I chages the spark plugs , the problem remains.
what are the possibilities , is it an engine problem ?

Asked by for the 2005 Audi A6 Quattro
scan codes and post so we can adv