Okay. Try something for me. When you get the vibration happening in all cases, push the tow/haul button and see if it goes away.
I think you are on the right path with it being in 4 cylinder mode. Most OEMs that offer this, struggle with this issue. Basically in 4 cylinder mode there is not enough power for the situation you are in and it makes what is called a drone. This can cause a vibration as well.
Ram trucks had this and they actually released software to put it in MDS "lite" mode. This means they don't bring it in a lower speeds or lower RPM to try and minimize this.
Let me know what happens when you do this and we can go from there.
SPONSORED LINKS
Friday, March 13th, 2020 AT 6:45 PM