2005 f150 5.4l 4x4
 

Hey anyone know what may fix my problem? As long as my rpms are about 1900 it won't do it but when it shifts sometimes it will buck at me acting as if the overdrive is trying to kick in and out it only really does from 40-50 mph. If I turn overdrive off it will not do it. And if I stay at a constant speed then give it enough gas to climb really fast to pass someone it bucks at me. Anyone may know what I could do to fix it

Welcome to the site..

Sounds ignition related. How many miles on the clock? Any prior/reg interval ignition work been performed?