Misfiring

Yes if you can do a cylinder balance test ,which involves pulling off the leads individually,use insulated pliers or wear rubber gloves to avoid shock,you can hear the rev,s drop at the cylinders that are working,and the one that,s faulty will hardly change the engine ,you can then substitute plug,lead,or coil at that particular cylinder and see if the fault moves or is cured on that cylinder.

Have to agree that its probably a coil pack breaking down.
Easy to change and not too expensive, but do bear in mind if one goes the others will probably follow suit fairly soon.
Thats what happened to a friend of mine with her vw and very common on Renaults.

You say you've replaced the plugs and leads so it cant be the usual individual pencil coils fitted on your year of car .As you suggest the coil would be worth checking or replacing as it can cause tracking / shorting , giving a misfire .

Hi . This is my first post so bare with me . I have a 1.2 2006 polo .Its my dads old car and there is very little mileage on it (circa 20k) I have a problem with a misfire and low idling speed .Rev counter drops down to about 5k rpm .My mechanic did a diagnostic on it and it said coil pack cylinder one .New coil pack fitted and within a couple of miles engine management light came back on and idle revs dropped again . He now suspects a dodgy injector as when he disconnected the relevant injector the car did not cut out but when injector disconnected on other cylinders car DID cut out .The car is driving fine just seems to go into limp mode every so often ..Any thoughts??

Also rear door lock seems to be siezed .But this seems to be a common fault with vw polo