My 06 has never done it. 0 deg out not plugged in and start it up it will go directly to 1000 rpm and stay there smooth as glass. If I use the cruise it will set to 1100 rpm and same thing, smooth as glass.

 

Any update on this? Mine has just started doing it.

 

I would call mine more of a flutter every now and then, not an oversized cam lope, even with a new fuel filter.

 

If you look at the tachometer and its not moving up or down and you hear what you think is a lope IMHO its some sort of harmonics from the engine or exhaust system. The only time I hear what some call a lope from my truck is if I don't let the grid heater run a full cycle when the outside temp is below 10 degrees and also I have not used the block heater.