Today on my way home from work my EA began to run a bit off song with a miss about every 30 seconds or so.

Got home and gave a few connector a wriggle and sometimes it picked up and sometimes not.

I then noticed that the temp gauge was going nanas sometimes it sat at the correct temp (near the L) and at other times it was all over the place.

It came good when I turned some corners and not others etc. etc. etc.

I reckoned it had to be a bad earth. I checked the one under the car near the starter and that was OK.

I then checked the one from the battery to the block and the bolt holding the earth strap on was nearly right out.

Tightened it up and everything is now back to normal.

Has anyone else had this earth lead bolt come loose?

I'm pretty sure I would have noticed it if it was loose when I did the welsh plugs 12 months ago.

Is it normal for this bolt to vibrate out?

i had to replace the wire connection crimps on mine as they were coming off and corroding.

Had that happen on my XF once (loose earth).

Also corroded battery terminals, loose battery terminal connections.

And in my EL I had a problem with my sound system, where the amp would suffer similar symptoms to waht you described (sometimes ok, sometimes dead). It was a mismatch fuse/fuse holder. The fuse holder was ever so slightly too big for the fuse (both were supposedly 5GA), so sometimes it rattled around.

Yes I remember having mine come loose on my EA and giving me similar symptoms.

Yeah had that one with sons amp in his car. Fuse not making full contact in holder. You must have bought the same brand of fuse holder. Amp would work then turn it up a bit and it stopped etc. Lots of head scratching to figure that one out.