Corsa energy 1.0L 2004 eml problem

Hi there,
I bought a 2004 Corsa energy 1.0L 12v last July which had sat for a year before I bought it (mileage is currently 42,700). Within a few days the eml was on and replacing the lambda sensor sorted it and it has been ok since. However, I was advised to change my timing chain due to it making a rattling noise so did this a month ago but when I picked it up from the garage the eml came on and was flashing. They kept it for a few weeks but have not managed to fix it and neither has a vauxhall garage. They have tried:
1) coil pack
2) spark plugs
3) crank sensor
4) double checked timing
5) stripped and rebuilt engine to no avail
The test showed up a misfire in cylinder 1 and they used camera to check all the valves but found nothing. They also did a compression test but nothing has been resolved. I now have the car back it is very juddery and rough when idling and the light starts to flash after a few minutes of idling but if you drive off quickly enough the light stays off. It is making very strange wheezy/whiny noise when i drive it and has very little power. Some advice would be great as it is my first car which is now not running and worth nothing to sell.
Thanks in advance!