Right, hope you're all sat down - problem is the inlet valves have corroded and started to withdraw into valve seats.
Full strip down of head, new valves, guides, springs, re-machine valve seats, lap and put back together.
We think whoever had the car for the first 60k has been running on low octane (cheaper) fuel and long motorway journeys have damaged the valves so they don't seat properly, compounding the problem.
Sent a strong letter to Saab as the warranty only expired in November !!!
Get car back in a couple of weeks.