Good evening, long time listener first time caller here!

I have a 2016 bone stock 2500 with 106K on the clock.

About 1.5K miles ago I got a mysterious rattling noise from the engine at about 1400-1800RPM.

Truck didn't run great, fuel mileage went down, and had some surging issues. Replaced the FCA, put new fuel in it from a different station, noise went away so I chocked it up to bad fuel.

During that time I showed a pending code of p020E that never triggered a CEL.

Well, noise is back intermittently, with it being worse on cold mornings and during active Regens.

Kicked the same pending code the other day(never triggered CEL), and this morning on the way to work it was 30*(that's freezing for us here in florida) and I was bellowing out thick white smoke until my engine got to about 150*, truck ran fine after that but still have a rattleing noise under acceleration, and now I'm scratching my head.

Does this sound like a bad injector?

Diesel shop I was able to get a hold of recommended taking the valve cover off and doing a visual inspection, so I'm working on that now, anyone have any advice on how to get the two breather hoses off of the valve cover?