Hi. New member here working on a 99 c70, 105k that had a bad surge with a light throttle at any speed. Cleaned the (electronic) throttle. The surge is mostly gone except off the line and into second gear, light throttle and 1500 to 2000 rpm. Runs great with heavier or full throttle. No diagnostic codes triggered. Throttle was reprogrammed by Volvo about 10,000 miles ago.

 

Possible a transmission studder?
Or possible a misfire?

BTW moved to the C70 section for more people to see.

 

you might have the recall problem known as ETM - electronic throttle modudle. I recently got this taken care of at my dealership for free after a bit of hassle. This site will give you the lowdown - http://www.vexedvolvo.org/