T350 lambda values

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I'm new to engine management software, so be gentle!
I've got an intermittent problem with the engine stuttering and cutting out. Most of the time it is fine though, which makes it hard to track down. A big thank you to EvoOlli for the MBETool software, which I have running on an old laptop under Win XP.
Logging the lambda values I get the following, which I assume is not right! Does this look like an earthing problem?
The engine was actually running well during this run.

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Thanks. I need to read up more on engine management!
I was concerned that the blue channel was dropping low during the warm up period and wondered whether there was a loose connection somewhere.

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Thanks Nick.
Hi Penelope. I have not done the earthing mod yet, it's on my "to do" list! Have you done it? Worth doing?

cheers
Stuart