I have a 2001 V70XC, with 130K miles - had it up in the mountains for the first time this weekend. I noticed going up steep grades, the engine was "pulsing" slightly.

At around 3K RPM, about every 2 seconds the engine power would cut back, very slightly (drop a hundred RPM's, at most), then come back with a bit of a surge in power. Not severe at all, but noticeable.

This happened with either automatic or manually shifting.

It happened both after driving for two hours to get up to the mountains, then after the car sat all day and heading back home.

Any thoughts?