I purchased a used 2003 996 cab w/ 6spd at 62K miles and had the 60K maint performed. At 73K it started misfiring and the shop had to replace all 6 coil packs and plugs. It ran like a dream for about a week and then it started surging around 3400 RPMs in every gear. It only does this when I'm going thru the RPMs slow to normal. At brisk acceleration, it doesn't happen. If this is the Variocam or Variocam II transition, why did it just start? Could it be that changing the coil packs caused it to start? Is there a fix? I often drive the car in traffic which makes brisk driving dangerous and the surge is annoying. Thanks for any help.