Don't know if this is germane but the "throttle actuator" is a known problem in 400/500Es. Typically goes out around 80-100kmi, and symptoms are: ASR light goes on, cruise doesn't work, and throttle enters "limp home" mode where there is a lot of free travel to the accelerator until any actual acceleration. Mine has done this twice, and both times shutting the engine down and restarting "fixed" it, but I know that sooner or later it will happen again.

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Steve
'93 400E