P0300 code

2001 GMC SONOMA
177,000 MILES • 4.3L • V6 • 4WD • AUTOMATIC
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ELI91013
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Truck is running lean, but drives good. starts acting up when i am going slow and in idle but not all the time. i have replaced fuel tank ,filter,wires,plugs,coil pack,distributor cap,and button. could it be my distributor itself?
Sep 18, 2019 at 6:06 PM
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SCGRANTURISMO
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Hello,

This sounds to me like you have a vacuum leak letting unmetered air into the combustion chambers of your vehicle. I would suspect that your intake manifold gasket is leaking. Here is a link below for you to go to explaining in more detail how to find a vacuum leak. Please pay special attention to the intake manifold gasket portion of the link.

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

Please go through this guide and get back to us with what you are able to figure out.

thanks,
Alex
2CarPros
Sep 18, 2019 at 9:09 PM
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JIS001
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Hello and welcome to 2CarPros. Just wanted to jump in. If you have a P0300 for random misfires and you believe your running lean, can you give us the short and long term fuel trim readings for both banks? Also if your scanner can read misfire data, can you got to it and tell us which cylinder misfire is counting the highest? If you can post a video of the misfire data on your scan tool of all 6 cylinders that would be even better.
Sep 18, 2019 at 11:00 PM
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