I have a 1998 V70 T5M with almost 90,000 miles on it.

A few days ago, while waiting at a traffic light, the engine dropped below the idling 900 RPM for no apparent reason, within a second or so it came back to normal. The Check Engine light did not come on, and the car ran fine afterwards.

Earlier today, again while sitting at a traffic light, the engine speed dropped but this time it stalled completely after struggling for a second or two, and the Check Engine light came on. I was able to start the car back up and pull over. After checking the gas cap and under the hood to make sure there was no obvious sign of problem (like something smoking), I started the engine back up again and it appeared to run fine. I drove home and the car did not have any problem the whole way.

Both times the car had been running for some time and the engine was at full operating temp. It was also not raining.

I searched on this board and found many posts regarding the Check Engine light, but none of the cases quite matched what happened to me.

Does anyone have any suggestion on what the problem might be? Also, will I have to take my car in to a dealer just to have the code read, or a good independent Volvo shop would be able to also, for a 1998?

Thank you in advance for your help.

Chie