I have owned 3 850 wagons, and this is my 2nd V70 wagon. I never had any engine issues with the 850's, but have had the same exact problem with both V70's, a problem I could never figure out. The issue is the engine will "stumble" on occasion. It will be running fine and then out of the blue it will sound like it's going to die, but only for a brief second then it goes back to normal. You can really feel it at idle, it feels as if it is going to stall out, when going down the highway it's felt more as a temporary miss (or occasional hiccup). On both vehicles I tried fixing it by replacing the plugs with NGK's, replacing the cap and rotor, and the wires. On both cars it didn't help. Anyone know what causes this? Is it possibly turbo related as 2 of the 850's I had were high pressure turbos, one didn't have a turbo, and the 2 V70's have the low pressure turbos? I really don't know what else the V70's have in common that the 850's didn't.

 

I just read your post regarding the issue with your V70's. If you are spending the bucks for OE spec NGK plugs, you should go for the Volvo brand plugs for this model, which I have never had trouble with. The peculiar thing about these V70's is the rubber and plastic connections and hoses in the engine compartment. Those little black/white vacuum control devices and hoses are often overlooked and neglected until symptoms arise like the ones you're experiencing. One of my current daily drivers is a 98 V70 GLT that I keep in optimum performance with preventive maintenance inspection and repairs. That's my hobby, making sure my vehicles are always in reliable and optimum operating condition to avoid the inconvenience of a breakdown when transporting myself and music equipment.