M54 suddenly running rough

[paramax55]

I have an e53 X5, manual transmission, with an m54 3.0. It does all highway driving, very little in the city. It has been idling smooth as silk. You have to look at the tachometer to make sure it is running. Yesterday, I took the wife to dinner. The car started and ran like normal. We did about 20 minutes of highway driving and, when we stopped at a traffic light, the thing felt like a Harley. So much so that the wife asked "what's going on with this thing?" And she isn't one to notice car problems.

It has not completely dropped a cylinder. It's running rough, but all cylinders are trying to fire. It's not throwing any codes related to running rough. I cleared the codes and they didn't re-appear while I was messing with it. It has had an intermittent cam sensor code for several years and it has a new sensor for that. But cam sensors make it run or not run. If you crack the gas pedal, and bring it up to 1,000 rpm or so, it's much better, but still there, so it's not related to the idle control.

Does this sound like a coil issue? I have no problem buying a set of coils, but I hate throwing money at "guesses" with vehicles.