When mine drops to ~1300 rpm, it revs itself back up to ~1600 and then drops again, then revs back up again. No idea what causes it. Doesn't do it on cold starts, usually does it when I stick it in neutral, and sometimes when I'm driving between 50-70 and take my foot off the throttle, it does it as well. Is yours similar?

Interested to find out what the hell causes it.

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It's at the corner of get a map, and fuck off