2006 5.7 driving steady speed between 35-55 the rpms will increase approx. 300 then drop back down, without increasing the pressure on the gas pedal. Will also occur with cruise control set.

 

Sounds to me like your tranny is searching for the right gear and is kinda stuck between the two. I used to notice that a little for the short period of time mine was stock.

Don't see it anymore. The 4.56 gears took care of that, plus with transmission tuning on a Superchips you can tune that right out as well...

 

Mine does this too, but I was under the impression maybe it was MDS kicking in and out?

I think it went away if I used tow/haul but i'm not 100 percent sure.

 

That's probably what it is. I misread the OPs post and thought he had an '05...

 

Yeah, well if it is that it's a bit of a nuisance. It's not enough to jolt the truck but just enough that you can tell it's doing it.

So now I just don't usually use cruise for that reason.

 

It's MDS turning ON/OFF. The RPM increase is due to the torque converter being unlocked in MDS mode.

 

Thanks for all the feed back. I thought my truck was the only one with this nuisance symptom.