Deere 9420R.  400 hours on it.  First time if did this I was coming down a hill on a highway.  It felt like something was tugging from behind a bit, then it just slowed down all the way to dead. It would not restart until whatever stays powered up under the hood (not the def pump) powers off.  I ran it all day on the road for an hour both ways to a 100 acre field, and made it home.  Worked another 60 acres and it started surging a bit.  Almost died once then it came out of it for another 15 acres.  Got to the end to turn around, slowed it down and it went all the way to off.  Had to wait before it would start back up.  No codes when I looked on the screen.  It may just be me, and it's only done it a few times now but seems like I'm always going down hill.  Pulling a Salford, in the field at about 10-11mph, but it acted up on the road also.  Anyone have an issue like this?