First of all, I know it is difficult to diagnose remotely without much to go on other than a vague symptom description. I'm looking for a starting point and suggestions. I asked about another issue in a similar way here and someone nailed it and my problem was solved. Anyhow, the title says it. A few months ago I had the same thing then it went away. Now it is back. When I have been driving a while and then am idling as in waiting for a red light, my engine will run a bit rough. It never stalls and the RPM is in normal range. Giving a little gas seems to smooth it out. Accelerating and cruising is normal. The plugs are all replaced about 18 months ago.No codes/warning lights indicating. What else to add? It is a 2007 5.4.

 

Given the info my next check would invlove the COP's or FPDM.

I know first hand how annoying the mysterious "chugs" can be.

2006 5.4

 

I would clean the throttle body and MAF sensor.