Front-axle death wobble (steering damper CSP applies)major
2018 is inside the 2017–2019 window for Ford's death-wobble Technical Service Bulletin (TSB 18-2268 — the fix instructions Ford sends dealers) and its follow-on Customer Satisfaction Program (a CSP — Ford's quiet goodwill coverage): a steering-linkage-damper replacement for 4WD trucks with 'sustained steering wheel oscillation after hitting rough pavement or an expansion joint above 45 mph.' It is a TSB/CSP, not a safety recall. Mechanics caution that the damper is a band-aid — the durable fix is usually the track bar, ball joints, or tie rods. Drive it over rough pavement above 50 mph and feel for the shake.
Sources: NHTSA complaint and recall databases, 2018 F-250 SD · Independent mechanic and Ford-tech channel transcripts (Super Duty)
$0
Damper under CSP
$400–$3,000
Track bar / front-end rebuild