Well then I guess I'm back at square one on my cold start rough idle. Found this post which seems the same as what I am so I guess I'll start looking at a possible injector problem.
http://www.peachparts.com/shopforum/showthread.php?t=78928&highlight=500sl+idle

Car runs/starts perfect after it warms up. Only happens for 30-60 seconds at first (cold) start.