trouble starting..stuttering and feeling down on power..again

[kooch_481]

sorry to bring this up again but yesterday my car a3 1.8t had trouble starting and once she did start when accelerating it seemed to stutter or misfire until the turbo kicked in..when i got back i left her idling for abit and there seemed to be little bit of smoke coming out the exhaust..

ive changed the fuel filter and put a green cotton panel filter in and it was all fine until yesterday..
has any one else experienced this problem ??

thanks