Back to the wonderful Idle problems of the 528e ('84). When my engine is WARM, the idle fluctuates cyclically between 750 and 500 rpm. Additionally, the car doesn't start well when warm and occasionally belches some black smoke when it finally starts (I usually have to touch the throttle a little to get it going) I have replaced wires, cap, rotor, checked the ICV etc, and replaced the majority of the vacuum/intake hoses. (I don't believe it is a vacuum problem anyway becuase the cold start is great and the idle is perfect until the engine is really warm).
Here is the question...Is it more likely that I have a leaky injector or fuel over-pressure situation (I know it isn't a low pressure problem becuase I pinched the fuel return line and the car died instantly), or is it possible that a blocked cat. could cause the problem. The exhaust stinks and the protective steel casing around the cat fell off a month ago. I believe the cat is the original w/ 150,000 miles on it...Any help would be appreciated.