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thanks for the reply. however, i have this list from mitchell on demand and other google searches. Specifically, I was wondering with my exact symptoms what you think the most likely failure would be. I did do a smoke test today on the intake and found no vacuum leaks in the intake that made a difference, only a very small leak I repaired at a vacuum tee. I also am guessing that I do not have the regina fuel system since I do have a MAF in the intake tubing. Looks like that will matter if I end up needing an oxygen sensor, which I have not tested yet.
I find this idling situation to be quite unique in that I have never seen such a quick oscillation in idle speed. Ive seen many vacuum leaks and i dont usually get a fluxuating idle for more than just a second or two, just higher than normal. also seen dead oxygen sensors that effect idle speed, but it happens much more slowly. Im not a Volvo tech specifically though, and work on all models, so I thought I'd ask somebody who sees these cars every day.