At interstate speeds van sways; has difficult steering & control
Losing the ability to control the van in low wind speeds is an abnormal issue. There are a few faults that could cause this issue though. The most common would be low tire pressure (https://www.yourmechanic.com/article/how-to-check-your-tire-pressure), failing suspension component (https://www.yourmechanic.com/article/how-to-inspect-your-suspension-system), or...