What would cause a Vibration when driving at speeds of 20 mph and greater?

What is your question?

It’s happening in a 2008 chevy express 2500 cargo van. When I get around 15-20 mph and faster there is a bad vibration i feel in the front of the van but can hear all the way to the rear of the van.

What makes this problem better or worse?

Nothing

How long has your 2008 Chevrolet Express 2500 had this problem?

Couple days