well had the rac out to it this moring, he said it could be coil pack problem(had all 4 replaced in august). what are faulty coil pack symptoms?

he also followed done a diagnostic check which showed no fault codes.
he also followed me to vw in doncaster, in which time the car drove fine but still was up and down on idle and seemed hesitant in 1st and 2nd gear. VW said they would not have time to look into that problem in depth but they also doe a diagnostics check as part of the service, which again showed no faults.
could it possibly be a coil pack problem causing the idleing problems???