Idle is a little bit smoother (especially in the morning when the engine is cold) but I'm still pulling CEL codes. The EGR valve is a big one (Code 5) that may have a play in the idle as well as a good cleaning of the MAF (Code 4). I'll post pictures within the next few days and keep everyone posted on the idle with the EGR connection and MAF cleaning.

Also, from what I've researched, the secondary harness (starter, o2 sensors, etc...) isn't exposed to the high temp engine heat so it doesn't break down as quickly? Does this sound correct?

__________________
1995 E420
1998 SL500 Sport
2009 E350 Sport
1995 S500 Coupe
1992 500 SEL