Hopefully i can help..
Nomally its the rocker cover gasket that causes oil smells to enter the cabin via the pollen filter which is directly in the centre of the scuttle area and just above the rear part of the engine...its quite common fail point on these engines..seeing as you have seen the leak at the rear side of the engine and that coil was replaced
great i am getting no warning lights or fault codes , so it should just be the rocker gasket , but why does the engine only miss at traffic lights & such and not when i am in motion . its quite hard to get revs up after about 3 mins of tickover at say traffic light
If the leak is seen to be coming down form the rocker cover gasket seem then yes..its just the gasket at fault..the coils have to come out anyway to that /not the sparkplugs but the tube in which the spraks sit or even take them out should be checked for oil as any oil forming around the sparkplug and the end of the ignition coils can cause the voltage from the coil to arc and thus damage the coil/cause a missfiring fault..I would asume they replaced the sparkplugs during the coil change - on the other hand if all the above is ok..then they can perform a compression test and ensure that all cylinders are even..if ok..then perform a balance test on the engine as per injectors.this must be done quickly to ensure the cat doesnt get damaged..they need to simply disconnect each one in turn. When it gets worse you know that was a good one. When there is no change in engine speed or lumpiness then you have found it - If it is always there at idle but goes away when revved, then it possible it be an injector problem..but start of with basics above first.dpending on the nature of the missfire then sometimes it can do that and even out at high revs until the engine back at idle..I do hope this helps helps further
thanks robert , ordered gasket £14 on ebay good news all round
Great stuff..if your doing this yourself ensure the mating surfaces on both the head surface and the cover are clean before the new gasket is put on..also ensure the sparks/coils ends are checked..once everything is fitted clean area with brake cleaner and leave to dry to get rid of the oil thats leaked out..