I have a 500E with 135,000 miles. Recently the idle quality has deteriorated and vehicle surges when coming to a stop. Under full throttle acceleration engine runs strong but also has surging at higher RPM's. I replaced caps and rotors 500 miles ago. No change to symptoms. Anyone have any ideas? Lou

Has the EA computer been scanned for codes?

Many times there will be a carbon build-up on the throttle housing/butterfly that causes LOW in-gear idle speeds. Cleaning normally helps.

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