Ok, so here is the story. I started the car up drove it about half a mile, shut it down. I then drove it about another half of a mile, shut it down. The next time I started the car it started to idle at only 400-500 RPM's. No smoke, no blow-by, oil level is fine, and the car has plenty of power. Besides this idle issue the car drives perfectly. I did run around 40 or so gallons of Biodiesel through the engine over the last 2 months, maybe this could be a cause...?
I changed the fuel filters yesterday with no change in any of the symptoms. Also, changing the ELR also does nothing. Here is the video I took this morning of the engine running at idle. I hope it helps to diagnose this problem.
OM603 Idle - YouTube
What could be causing this? Any help or insight would be awesome.