2007 VRS TFSI Combi occasional continuous misfire

Good morning, 

I have a 2007 VRS TFSI, its got 129k miles on it, 99% of the time it drives well, but every couple of weeks, usually on a hot start, I will have a continual misfire, sometimes for a minute, then yesterday it was for about 15mins, VCDS says cylinder 4 misfire, I get a flashing then continual engine light. After it has its wobble for a bit, it usually just recovers and then drives well for another couple of weeks, sometimes it recovers after turning off and on, others it just starts running on 4 again randomly. 

Plugs replaced, coils 3 and 4 swapped round but fault didn't follow, am I right in thinking the only thing left really is the fuel injector? What else can die in there, cause a continual misfire for several minutes, then recover and drive as normal for weeks? 

The car has never been walnut blasted as far as I'm aware, I do from time to time have a little shake to the idle, which seems to be cylinder 2 (watching live misfires on idle)

Any help or advice would be greatly appreciated.