My Omega is a 2.5 V6 CDX Auto.

HELP!!

After thousands of miles not missing a beat, yesterday it started to idle a bit rough and to hunt. I ignored it and carried on with my journey cruising at a nice steady 70 down the motorway on cruise control. Then after about 20 miles it started missing, a little at first and then over the next 10 miles it got worse until it died altogether. No way would it start and I had to call for rescue to get home.
Today I tried again to start it. Every time it just fired up and died immediately. Only once did it run for about 10 secs then died as soon as I touched the accelerator. Noted that all the warning lights went out as normal.
I suspected a fuel feed problem. I removed the petrol feed and return pipes at the engine and stuck them in a jar whilst cranking. Petrol came through OK. I checked the fuses, especially fuse 16 - all OK. I checked all other electrical connections but it made no difference.
Any ideas?
Could it be one of the sensors? - which one?
Andy T