Hey, first; I would have the car scanned for trouble codes. There are a number of possible issues with misfiring; get the car scanned, post up those codes and we will do our best to help.
fuel delivery, ignition, etc.
Also, give us some more history on your problem; how many miles are on the car and any work, that has been done recently. When does the problem crop up; when cold in the morning, does the problem go away; at certain times? etc. etc.
The 1.6L engine; was not USA spec, so we are not as familiar with them. That being said; finding drivability problems, are pretty much the same no matter which engine you have.
You can get a VW specific scan tool; pretty cheap online, check out these on amazon UK: the vas 450 or even the very inexpensive vag 305 can get your vw specific codes, help you and us diagnose your problems.