I have a 2000 caravan with 302000 km on it. Up until now she has run great. The other morning I went to start it and it fired up but with an extremely rough idle, even died a few times. Finally after running the **** out of it for a few seconds the idle returns to normal and the van runs great. There is a little smoke during the rough idle. Plugs only have about 2000 Km, there has been a small knock for quite some time on startup but that is just a sticky lifter. Seems to only do this after van has sat for a while and cooled down. Am I looking at EGR problem here or fuel pressure regulator? No CEl codes apparent.

 

It sounds like the egr is malfunctioning..

http://www.e38.org/e32/rough_idle_an...mate_guide.htm
^ I would go through this guide and attempt to narrow down the problem