I think someone mentioned the leaking injector idea on this post pointing out a leaking injector could cause a problem at idle as it continues to feed excessive fuel into the engine when it's not needed. I suspect that the internal part of the injector may be defective, thus cleaning really wouldn't do the trick. They also suggested if you are changing out the injectors, to also replace the seal and the holder to prevent hold ups on installations as these parts are commonly not a reuse part.
I am curious and wanna ask anyone out there if they know what the vacuum line coming off the fuel pressure regulator going to the air inlet housing actually does, and if it doesn't work, what the effect would be?
"Tell me and I will listen, Teach me and I will learn, Show me and I will accomplish, Involve me and I will succeed."
'84 300SD 256,000 Gold on Brown (Mileage Award)
'86 300E 246,000 Blue on Tan