🤕 Ok , worked on many cars including this 1600 Duretec with a misfire leading to a code . I removed the plug leads and plug covers to discover all the access holes full of coolant/water . I have never stripped one of these engines down , so is this a fault indicative of head gasket problem or trouble surrounding something to do with the inlet manifold system. Unfortunately , I have not looked at the engine oil for discolouration. I do know that the owner has run the oil level low , it did drive here to my place but with misfire of course from water ingress . 
Any thoughts someone out there, please. 

Core plugs on top of the cylinder head.

Yes I have just read a a very interesting thread on something similar. Unusual, but I’ll do a compression check first . 
I the rocker cover off to change them , not had a full look yet , sorry . 

Checked further and compression at the moment can’t be checked as my gauge is fitting due to long reach threads . 
However the water pump looks the likely suspect. As its throw a fine film from the aux  belt area . So correct me if I’m wrong, it must be throwing it up through the camshelf guard if it’s filling the rocker cover . 

Oh DEAR, Wrong again , not water pump , but still a one core plug finding coolant after a very lumpy run . I noted that there was some hase of water vapour as it was misfiring , so not convinced its just core plugs .Confused???

Think I need to get another Compression gauge as the threads on my pressure gauge dont reach on this Ford model.