memtb wrote:
First...The steering initially was "nervous" or "twitchy". A small movement of steering wheel, caused a "pretty good" response. This seemed to get much better (or I got used to it) the farther we drove!! It has brand new tires, could this have been caused by new tires that just needed a little road time?
I have driven E-series vans for over 30 years, although admittedly never a E450.  My experience is the ALL have some what "twitchy" steering.  I have learned to just relax and use the smallest amount of steering input possible especially when on the highway.
Depending on how many miles you drive, you might need to have the front end checked for alignment/wear as often as every 1-2 years.
If you are carrying any heavy cargo, try to locate it AHEAD of the rear axle.