I still couldn't figure it out, so I took it to the dealer for diagnostic.

$171 for for 6 spark plugs and a burnt spark plug wire. Drove 200 miles, ran fine. On return trip ASR light came on, but never went into 'limp mode." Moved it from one parking place to another and both SRS and ASR lights came on, but went out after a few moments. Does it ever stop? At 131k, I'm really disappointed in MB...

Bob