2000 s70 surging/hesitation (O2 sensor?)

[Caberguy]

Well, that doesn't seem to have had any effect on the surging/hesitation problem. Too soon to tell if it's still running too rich.

Any other ideas before I drop the money on a Xemodex ETM, which may or may not actually fix the problem?

[CliffJFraser]

I have a 2000 V70 2.4 non-turbo 200k kms that is starting to have the same symptoms, minor surging or hesitation, at variety of speeds and acceleration, more annoying that a major issue at this point. Just wondering if you resolved the issue?

[Scholz]

I was having a similar issue for a couple months with my 98s70t5. It was frustrating because for the most part the data points were not telling me anything. My Fuel trim adaptations were negative like yours. My MAF was reading within spec as far as i could tell with my scantool.

Basically I just went down the laundry list of things that could cause this.
1st. Vacuum Leaks (I was good.)
2nd. MAF (Was reading 'accurate' and was not lazy)
3rd. Upstream Oxygen Sensor (Responded immediately to artificial lean/rich conditions)
4th. Idle air control valve / Throttle Body. (I had serviced these during my PCV overhaul a few months ago and did not suspect them to be the culprit. Mind you I have a 98, so no ETM)

After that, I sat down with a glass of my favorite vodka and convinced myself it had to be either the MAF or the Oxygen Sensor anyway. I cleaned the MAF and in the process discoverd that the safety Torx bolts had been mucked with by the previous owner so I feared i possibly had an aftermarket ebay special in the housing or something. I purchased the MAF first on a hunch and it completely cleared it up. I ordered the oxygen sensor at the same time as they're due anyways but I haven't replaced them yet.

The new MAF read slightly different at idle (perhaps .1 to .2 g/s)
A bit longwinded but I thought i would give you my experience if it helps at all. Good luck.