Idling issues

1994 GMC TRUCK
305,000 MILES • 4.6L • V6 • 4WD • AUTOMATIC
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CHELSEY EDWARDS
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My truck idles really rough to the point it shakes the whole truck and then shuts off this happens when idling, at low speeds and stops. I have checked sensors and replaced fuel filter not sure what else could be causing this?
Nov 5, 2020 at 1:48 PM
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KASEKENNY
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If this just started happening then the most likely cause is a vacuum leak. Let's run through this guide and go from there.

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

If this does not help then we need to check for codes but I am pretty sure we have a vacuum leak so I would be surprised if that doesn't help point us in the right direction.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Let us know what you find. Thanks
Nov 5, 2020 at 2:13 PM
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CHELSEY EDWARDS
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Okay, I know I already asked and I haven't checked whether it is a vacuum leak but I just thought I would add a video for reference. I will check for a vacuum leak tomorrow.
Video (Click to enlarge)
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Nov 5, 2020 at 6:54 PM
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KASEKENNY
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That does help. Thanks. It does point to a vacuum leak as well so clearly that is where we need to start. If you have no check engine light the I doubt it is a misfire but if there are no vacuum leaks that will be the next thing we need to check. If you have not replaced ignition components in a while, that would not be a bad idea to do anyway but clearly start with a vacuum leak as you said. Thanks
Nov 6, 2020 at 2:25 PM