I have a f150 2016 3.7 ecoboost and everytime i put it in reverse and sometimes drive the whole truck shakes 1 big time then i can proceed what i am doing its not vibrating or shaking a constantly just one big shake to the point of my head bobbles and then it dosnt do anything can someone help please cannot find the answer online

 

Driveline engagement will always involve a bit of a bump. If you get too much of a bump and it's idling normal (@600 rpm once warm), it's a sign that your u-joints and/or differential are worn, and/or a broken leaf spring, and/or the axle is not being held in position on the leaf pack.

Or you are driving around in 4lo.