Jumped on the forum tonight as I'm having the same issue described by jacarmona91 and Ron 52. I also have a 2006 F150 4x4 Ext. Cab 5.4L V8. I rolled over 85K miles today and have noticed this shutter at low RPM in OD too for the last couple of months. It seems to have gotten a little worse lately. I only notice it though with low RPM in OD. At higher RPMs it doesn't happen.
I have not changed spark plugs yet, but I've assumed it was a transmission issue. Transmission fluid has never been changed yet either.
What's your suggestions?
2006 Ford F-150 SuperCab Lariat 4x4
2" AS Leveling Kit | DWV Intake Mod |18" MagnaFlow | Gryphon Programmer
285/65-18 Nitto Terra Grapplers | Hunter Chrome Bull Bar