We had the same problem on our 06 plate 1.8TDCI focus, right pain in the arse. Had a mind of it's own, engine system failiure light would come on at the start, then go off, then came back when it wanted too. I decided to try changing the glow plugs and the lead.

Couldn't beleive it, doing that resolved all the problems, no engine warning light and all seems to be running better than it has for a long time......

Then all of a sudden whilst driving down a dual carriage way at around 60 miles an hour, all power went from the engine, running very lumpy, managed to limp off the carraige way and park up. turned the engine off and waited a bit.

Fired it back up and everything back to normal, bit worried now as to when it's next going to mess about...... seriously thinking about flipping it for another car less technical.

Graham.