I was heading out of town this afternoon in my 2000 F350 and suddenly the engine lost most of it's power and sounded really bad, rattling a lot. Turned around and limped home. The local body shop was able to pull a P1316 IDM code but nothing further as it didn't support diesel powertrain codes.
Did a little googling around and came across this youtube vid:
Using a temp gun, the passenger-side exhaust manifold actually cooled down from 150deg F to 110deg F while the engine was idling in the driveway, whereas the driver-side manifold stayed at a consistent 200deg F.
I pulled the passenger-side valve cover off and sure enough, the UVCH connector had popped open/off. Fortunately it had just happened and the contacts were all good. I snapped the connector back on and found a washer that matched the size the guy talked about in the youtube vid and slid it in behind the connector latch and buttoned the engine back up. The engine runs perfectly again.
Easy fix, and I almost had the truck hauled in to a diesel mechanic. Sometimes it's the simple stuff that breaks.
Hopefully this might save someone some money before they go replacing an IDM.