intermittent idle

1986 MERCEDES BENZ 420SEL
150,000 MILES • 4.2L • 2WD • AUTOMATIC
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STEVE SHERIFF
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  • 1 POST
engine continues to idle high for a few moments then idles low for a few moments. but runs good on open highway.
Aug 20, 2016 at 2:07 AM
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RENEE L
  • MEMBER
  • 1,260 POSTS
Hello,

It sounds like you have a vacuum leak, here is a guide that should help you

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Pleas let me know what you find out so we can continue.
Aug 30, 2016 at 2:22 AM
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