The issue is super weird because the idle doesn't mess up every time. Ford did tell me before they had smoke tested it though and all was fine. (I'll ask them to redo though, have car in for service soon anyway)

Anything else you can think of that may cause this kind of issue? I have a Carly obd reader so there's some live data values I can look it, but not sure which to watch for the idle

Wish there was a specialist ford garage here in Scotland, but doesn't seem to be