[W126 Coupe] idles rough when properly lean

[Dick Spellman]

Spraying any carb cleaner in the air intake  will simply stall the car if
enough gets in there And I use a spray cleaner for injectors and intake in
there once a year with no problems.  But, you need to spray outside working
your way from the base of the intake manifold upward to try and identify a
leak.  In other words, if a vacuum leak exists the cleaner will be sucked in
by the vacuum and the engine will momentarily run smooth.  Nathan used to
use a propane torch (not lit) just leaking the propane around the manifold
to see if the engine smoothed out.  In either case, you do not want to come
in contact with any source of heat or spark when doing this check!

Carefully unclip each plug metal boot at the plug.  If you tug on the spark
plug cable you will end up with a broken plug wire.  I use a rubber tank
cleaning glove and a rag so as to not get the jolt the plug wire delivers.

Please remember I, like you, are a DIY'r and not a mechanic, please be
careful, etc. etc.

Dick