The engine of my 2000 S70 with 201000km (125000 miles) and base non-turbo engine surges slightly up and down when being driven on the highway with the gas pedal held in one position. (Cruise control, air conditioning all off). The surge is not noticed on the speedometer or tachometer but is felt by driver and passengers. No warning lights or OBDII codes. I am highly suspicious of the original Magneti Marelli ETM (p/n 58106,038 white dot). Can anyone who has had a similar problem comment on whether this condition is serious or not. Another issue, possibly unrelated, is that the car occasionally stalls when accelerating from stopped, generally in the middle of an intersection.
Thanks