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RPM drop/fluctuation

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Old 01-03-2014, 01:15 PM
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RPM drop/fluctuation

First Post.

I drive a stock '90 RS V8 5L. When I'm "idling" in gear. (foot on the brake at a stoplight or foot off the brake but no gas engaged) I notice the engine drops 5ishRPM and then back to idle rhythmically. In some cases this causes my engine to shut off while in motion so it is dangerous.

Sorry if this is poorly-worded. What could this be? I have very little car experience.
Old 01-04-2014, 08:28 PM
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I moved this to the TBI forum. Figured you're more likely to get useable responses here.
Old 01-04-2014, 09:46 PM
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Re: RPM drop/fluctuation

sounds like bad spark plugs/timing...
Old 01-05-2014, 03:25 AM
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Re: RPM drop/fluctuation

Originally Posted by zero13
sounds like bad spark plugs/timing...
Thank you 57kid. And zero,

what should I do about it?
Old 01-05-2014, 10:48 AM
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Re: RPM drop/fluctuation

well,obviously change your plugs..no need to get fancy schmancy ones,just trusted durable..ac delco,etc.....make sure your timing is proper too..use youtube for searching how to articles...use these threads,but if youre a hands on guy(or not)..use youtube because people show you video versions of how to do things...you'll learn alot,and take more pride in your ride!!!!
Old 01-05-2014, 11:32 PM
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Re: RPM drop/fluctuation

Cool, thank you for the help!
Old 01-22-2014, 01:34 PM
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Re: RPM drop/fluctuation

Check for a vacuum leak.
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