Mk3 Tdci Engine Issue Non Start

Hi I hope someone can help. My wife came home in our mondeo 2ltr tdci 2003 130bhp with no head lights. I changed the bulbs and fuses and no change. Gave it up as a bad job went to start the car and it was dead. All the dash lights came on but it wouldn't crank. I left it over night and came back next morning both the lights worked and the engine started. Since then it's cut out or not started a number of times. When you leave it 15 min it starts again fine. no coil or engine lights come on though the clock light continues to flash at the same speed. When/ if it starts the clock light goes out.

I've changed the battery had the earth leads checked, and chaned the cam position sensor.

When it's running there's no issues other that it's alway had a bit of black smoke when you thrash it.

Can anyone help we rely on the car for work and the garage just says leave it with us and don't seem to be able to sort it.

Thanks.