It's totally doable with the manifold in place. Just unbolt the distributor air piece on top. Key is getting the wire harness junction box out of the way and the throttle body out.

Watch the BavAuto video. You have to get the bolts off blindly, but you can feel them if you stick your arm under there. It's a blind R&R of the 2 retaining bolts for the valve itself, and a blind install for the hose that comes up from under the manifold, you have to press it on the valve and twist it up into place. It's all blind, but doable if you're familiar with the orientation.

I replaced mine, and all hoses and the updated dipstick tube in June and took me approx 7 hours DIY start to finish taking my time. Would be able to do it in half the time now that I know what I'm doing.

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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