2004 sportka misfire cylinder 4

[Chain-time]

Hi folks,

Hope everyone is keeping well,

Wonder if someone can give a few pointers, the wife's 2004 ford sportka is throwing a wobbler, 

Starting from cold on tickover you can hear an uneven idle (very slight misfire) once warm i.e motorway speed etc and then switching off, coming back to start again a short time later, the engine starts but appears to only run on 3 cylinders and shows around 500rpm for a few seconds before dying. 

Go to start again straight away and starts up fine but the slight misfire on idle can be heard. 

 

Car pulls and drives fine otherwise

Plugged in the scanner a few days ago and said p0304 cylinder 4 misfire. 

 

Changed plugs

Leads

Cam cover gasket. 

 

Was serviced last may approx 5-6k miles ago and had fuel filter, plugs leads, oil n filter etc. Car has only done 56k miles 

Currently getting around 270 miles from a full tank. 

Any thoughts as I've read it could be loom  or coil pack?

 

Tia!

Rob

[Chain-time]

Also checked the spark plugs ( have covered approx 60 miles on these plugs and have a white glaze to the electrode cap, indicating a lean mixture.. 

All 4 plugs are like this so doubt all the injectors are blocked up or burnt valves on all four cylinders.. weird