You might wanna check that notrious overload protection relay that everybody is griping about on the forums. It should be back behind the battery hanging off the side of your engine control computer, it's the one with the flip top and ATO style fuse under the clear flip cover. You also might wanna pull your idle control valve, clean it out with some carb cleaner and make sure it's opening and closing properly, these do have a tendancy to either stick or plain burn out after a 100k+ miles on jetronic systems. As far as I can tell, MBZ ignition systems of this era are extremely sensitive to plug gap as well and it's pretty short, like .032 or somehting along those lines.