Had the exact same issue on my ‘18 JKU a few months ago. Turned out to be the exhaust crossover rattling against my MORE skid plate - only under easy acceleration. I had bashed it on a log (so it did it’s job), and it got knocked a hair closer to the exhaust. I ground away part of the skid plate (there was like 1mm clearance on one little lip of the plate when first installed) and the noise went away. Now it’s back but I think probably unrelated to that skid plate. Same exact sound, just less frequent. I’m gonna get under it this evening and look at the heat shield, etc. I’m confident it’s something that simple.

Any updates would be greatly appreciated. I have suspected the sound may be coming from the vapor (charcoal) canister. Thoughts?

Solved: It was a heat shield vibration occurring between 1500-2500 rpms. Some small spot welds had failed. Was able to resolve with a strategically placed hose clamp.