S70 Idle RPMs drop

[grzesiekpl]

Hey guys,
I'm trying to figure out what's going on with my s70. It's an glt model, 2.4l 160bhp engine from 1998. I used to have this problem in the past. Last year I find out that my O2 sensor (2nd one) gives no voltage at all. Replaced that and my volvo was working like a charm for about 7k km. Now I'm struggling same sort of problems. It looses power while getting around 1k RPM, and while stopping my car it goes under 1k RPM and then it stops. I can't even start it up after that.. The engine managed to turn on while I had my foot hard down on acceleration pedal.
Any ideas what is going on with it?
What I've done so far:
- checked voltage on o2 sensors. 1 gives 0.4V idling 2. 0V shows on my obd2 adapter
- checked voltage on MAF. It shows 0.3V (is it good?) Can I plug it off to test if its a problem?
- inspected my car for any leaks in engine chamber.
oh, non errors in ECU..

Btw. It started to show this "SERVICE" light like 100km ago. Is there any possibility that it causes a problem? And is there any way that I could switch it off? Tried almost any method I found on this forum (tried 15s milage reset having my key on II possition)

[E Showell]

The idle dip on '98s is well-known and has been written about extensively on this forum. I recall reading one post about "Campaign 81" I think it was that one poster said had resolved the problem but screwed up his gas mileage, if I recall correctly. I asked my dealer about Campaign 81 and they looked at me like I was from Mars. I've just lived with it, but my fluctuating idle never caused the car to shut down.

As far as the service light reset -- the only solution I am aware of that doesn't involve purchase of the somewhat expensive Draper tool or having the dealer reset it periodically, is to remove the lightbulb from the dash. That's what I did (but only because I had to replace other bulbs in the dash cluster that had burned out). No more service light!