Engine misfire

Hi everyone, could use some advice on a problem which has come about in the past couple of weeks. My mk4 1.6 Golf seems to judder when idling. Have taken it to main dealers who said needed new ignition coil. Had that done but problem remained, so I changed plugs and remaining three coils, however the engine shakes when idling still.

Have had someone look at and has advised compression test, also believes one of the injectors may have gone.

Need some advice as to what it could be?

Check the compression first.