Our Toyota truck revs its engine sometimes by itself, like a ghost is stepping on the gas pedal for a few seconds. I always figured it had to do with emissions, but maybe they have an inherent design issue that goes way back.

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1985 380SE Blue/Blue - 230,000 miles
2012 Subaru Forester 5-speed
2005 Toyota Sienna
2004 Chrysler Sebring convertible
1999 Toyota Tacoma