Random rough idle. Goes away with a little revving

[Matticus]

Anyone know what causes this?

2012 Expy. I'll be driving and suddenly the engine will drop in revs and idle really rough. Shakes a lot. It will immediately go away if I rev the engine a little. It doesn't happen often, but it seems like it's always when I pull into a driveway. I'm wondering if it's related to odd throttle response I'm getting that I posted about in https://www.expeditionforum.com/threads/lunge-hesitation-at-low-rpm-caused-by-tps.42618/

 

[JExpedition07]

First thing is first, see TSB for low RPM stumble and stalling on 5.4 3V engines. The first step is to replace the VCT Solenoids on both banks, these are often the culprit for shaky idle and stalling. It does sound like you have rather loud phaser knock until you hit the gas then it went away even after you idled back down. Some knocking can be normal if the VCT phasers still operate within tolerance but it seems loud here. To replace the solenoids the valve covers need to be pulled unfortunately.

If solenoids don’t solve your problem here it’s going to require a timing job. New chains, phasers, oil pump and all that good stuff.

 

[Matticus]

Hmm...motor is new. Replaced last year. Guess I'm going to bug the guy that did the swap and see where that leads