I am almost certain the Idle control valve unit needs to be replaced.

Doing this (in my case, repairing it, not buying an expensive new ICV) --- completely cured the same problem in mine back in around 2002 and it never recurred.

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1991 560 SEC AMG, 199k <---- 300 hp 10:1 ECE euro HV ...

1995 E 420, 170k "The Red Plum" (sold)

2015 BMW 535i xdrive awd Stage 1 DINAN, 6k, <----364 hp

1967 Mercury Cougar, 49k

2013 Jaguar XF, 20k <----340 hp Supercharged, All Wheel Drive (sold)