'87 535iS part throttle stumble

["French, Cary (CLFR)" <CLFR@xxxxxxxxxxx>]

My '87 535iS has 125,000 miles and has for the last 40,000+ miles stumbled
(surges, misses) when slightly coasting at part throttle.  This stumbling is
not apparent when slightly accelerating (accelerating at a rate of 1+ miles
per hour).  The stumble is not apparent at full throttle or coasting with
the throttle closed.  Idle has always been mildly rough.  I have had the
injectors out for cleaning, reinstalling them with new O rings.  Replacing
spark plugs (with stock) has little effect.  My guess is either a vacuum
leak, O2 sensor, or something with throttle position.  Any suggestions are
welcomed, E-mail me direct.  Thanks.

CLFR@domain.elided
'87 535iS

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