Runs and idles rough I did a complete tune-up

1992 CADILLAC SEVILLE
155,081 MILES • 4.9L • V8 • 2WD • AUTOMATIC
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ASHLEY31MAR13
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  • 1 POST
Earlier today I did a complete tune-up on my vehicle after I finished it, suddenly, it's not only idling rough it's running horribly now. I don't understand why.
Jul 9, 2022 at 7:05 PM
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STRAILER
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The first thing that comes to mind is did you mix the plug wires up? here is the firing order in the diagrams below so you can check it out. Also, when you did the tune up did you replace the distributor cap? If so, there is a ground strap or wire that must be changed over when the cap is replaced. And lastly did you use the OEM spark plugs and did you set the gap? It is easy to crack a spark plug which will make the engine misfire. Can you upload a quick video of the engine running so that I can tell for sure what's going on? You can do so in your response. Check out the diagrams (below). Let us know what happens and please upload pictures or videos of the problem.

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Jul 10, 2022 at 3:39 PM
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