Post up the details of the van, lets see if we can figure it out. Been a while since i diagnosed a dodge speedo issue. They were pretty much trouble free.
Lets see, check engine light on? Cruise work? Sensor is on rear end if i recall. If cruise doesent work and check engine light is on its usually the sensor. Lemme go look
I am sorry I had to leave early with the conversation about my van going on.
Frank....the only thing I have to say is that As I drive the speedometer fluctuates at a slow pace. For instance driving at 60mph or more. It will say 30 and slowly to 45 then slowly going back or where ever it wants to run and the O dometer rolls as it should only at a slow pace