A bad O2 sensor would result in pretty poor gas mileage as well. Is your gas mileage pretty poor? Not sure about stuttering, but bad gas mileage would be one of the giveaways for the O2 sensor. You may want to get the CEL scanned again and see what the code is. Autozone does it for free.
The coilpacks are VERY easy to install/remove. If you can change your oil, you can do the coilpacks. In the MKIV forum on vwvortex, they have a stickied DIY thread that covers everything. Look in there and I think there's a picture step by step of doing coil packs. If you can't find it but convince your friend to try theirs out for 30 minutes, I can take some snap shots of my car and show you how to do it.I do know someone with the same engine, but I'm not so sure she would care to share it with me. Are the coilpacks pretty easy to take out and put back in?
Thanks for that VW forum link!