Have had two Windstars. Never had this problem either. Have a lift and a power wheelchair as well. I don't sit in the chair when I'm in the van, but it's still heavy.
We've had other issues with them. Last one was a hard start.
This one, the ac blew up and then another time the transmission had to be replaced.
Wish they were still making these vans! They work the best for me. The Flex I thought was going to be the replacement, but it didn't work out.