If it's not the coil pack...then what else should one check?
There are more things that could cause it and i've had all of these
* Do you still have a diaphragm-type diverter valve? Change for piston-type 'Revision D' valve, part 06H 145 710
D?
* You've changed the coils - have you changed the sparkies?
* When was the last time you gave your car an 'Italian tune up'?
* Using the correct grade of fuel? 98+ RON?
* Is it 'hunting' for revs, i.e. dropping to 600, then peaking up to 1,500-2,000 rpm? PCV might be kaput...
Hope you get it fixed.