Good info about running way rich. Got my o2 working last night, will continue to monitor.

re valve guides / head job - Headwork was done by local machine shop that does most of the MB + BMW head work around town. Everything looked BRAND NEW when they came back, including blue dye around the valves.

Are all MB v8 stem seals the same ?
Maybe they just installed what they had in the box labeld "MB v8 stem seals".
You would think they would know being a head specialty shop.... but things happen.