That is a strange one, another good thing to check when you have weird electrical symptoms that seem to make no sense, check all your earth points (and positive battery terminal too, it's a PSA thing lol).
I had a Rover 214 years ago that suddenly wouldn't run right, dies at idle, tach erratic & said it was overheating. (It's a Rover, first thing anyone thinks is head gasket!). That was just a loose battery earth terminal. Would've made a tidy profit on that £20 car as it was pretty clean, then the gearbox shat the bed lol so it got crushed)
I had a Rover 214 years ago that suddenly wouldn't run right, dies at idle, tach erratic & said it was overheating. (It's a Rover, first thing anyone thinks is head gasket!). That was just a loose battery earth terminal. Would've made a tidy profit on that £20 car as it was pretty clean, then the gearbox shat the bed lol so it got crushed)