HI this is starting to stress me out now. P1364 - 35 - 00 cylinder 4 ignition circuit : open circuit.  Replaced all coil packs and plugs. Checked wiring on top of cam cover, probably has been better in its life but still looks ok. Drives ok till up to temp, then develops a misfire. Any help would be valuable.

14 hours ago, skidmoose said:

Drives ok till up to temp, then develops a misfire.

This is the clue, you have a wire going to cylinder 4 coil pack that when it gets hot goes either open circuit or high resistance (so it appears open circuit since it can't carry the current). Best plan is to replace the wiring to at least cylinder 4, and maybe all the cylinders since if one wire is dodgy now others could soon.