Hello,
Just thought I would post this to help others. Our 99 S70 (with 110K miles on the clock) had exhibited random, intermittent surging, along with a low idle of about 600 RPM. At this low idle, it was running rough.
Dealer suggested cleaning the ETM. I have a copy of Vadis, it doesn't mentioning any cleaning procedure, just R&R. Actually, it describes a super long R&R procedure that would take a couple hours & a special tool to do. I looked at it, thought they were a bunch of Swedish fools, and had it off in about 10 minutes. Didn't follow their procedure at all. Didn't need to.
Anyway, carefully removed the years of carbon accumulation around the butterfly with carb & choke cleaner. Put it all back together.
Started up, ran for few miles and couldn't believe the difference. Idles smoothly at the 850 RPM spec.
Anyway, if your car is randomly surging and idling below 850 rpm, clean the ETM.
Did I say that Vadis sucked? Oh yeah, I did. Oh well, I'll say it again; Vadis sucks.
Jeff