Good morning! I would be glad to help you out with stuttering/vibration concern when loaded should you need further assistance. Just shoot us a PM with your VIN and dealer name/location, and I'll get right on it. To send a private message, just click on our username and select "Start Conversation". Thank you!I have this issue when loaded. No cap. Some posted about this in 2022. https://www.f150lightningforum.com/forum/threads/vibration-between-45-55-mph.13384/#post-286963
I have the issue but no cap. I have a sturdy Diamondback HD cover on the back that probably weighs in the neighbourhood of 140 lbs.It is interesting that it seems most (perhaps all?) of us that are experiencing this issue have a cap on the truck. I do believe this issue started after I put it on.