I would take some WD40 and spray your vacuum hoses as you may have a leak somewhere, coilpacks you can pop the engine cover off and make sure they are seated down all the way, on my old VW they used to pop off.

Cleaning the ICV/throttle body would probably be helpful as well but on a 4.8is i'm not sure how to tell you to get them off. If you have no vacuum leaks and MAF is ok I'm assuming idle valve or throttle body related.

Sorry I'm not much help with my 3.0!

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2018 Ram 2500 6.7L Cummins 68RFE
19k miles -Bright White/Black - Big Horn Sport - Crew Cab Short Bed
2013 X5 35D (CEO's) - Born on 5/17/2013 -
82k miles - Alpine White/Cinnamon Brown/Premium Pkg, Sport Activity/Premium Pkg and Sound/20" Style 214/Running Boards