Hi Tony,
A fairly regular problem on Fiats (mine included) is for the temp gauge to have a mind of its own. In my case, a subscriber on here said don`t worry about it. After a while, the gauge settled down and is back to normal.
If you think the van is running OK, give it a chance to sort itself out. If it persists, you might have to change the sender on the engine block. What you could do in the meantime is to check the electrical connections at the sender and behind the dash. I think I remember reading that taking off the front of the instrument cluster can be a pig of a job on some models.
Best of luck.