Hi,

1999 S-type, it stops if left in idle for a few minutes, and just before stopping the car is slightly shaking.

Tried to check with obd. When idling it shows
fuel system status: open loop (system fault)
maf sensor: 8.86g/s
bank1/bank2
o2 sensor 1: ~ 0.030v/0.035v
o2 sensor 2:~ 0.015v/0.015v

If I rev the engine for a short while, the o2 sensors fluctuate between 0.05 and 0.9 and the fuel system status switches to 'closed' and maf sensor shows: ~2,78g/s and engine runs fine.

If in that state the car is left to idle, the o2 sensor values go back to same values as above and STFT starts rising about up to %50 and after a short while the fuel system status changes back to open loop again and starts running rough right away when it switches to open loop.

I thought the problem might be the O2 sensors but I have some questions:

* Is it possible that all of them have been degraded in a similar fashion so they show similarly wrong values?
* Any ideas on what else might be the problem?
* Why do the sensors appear to work when I rev the engine? (maybe because of higher air flow through the sensors? or warmer air?)

Thanks,
Evren