I guess I gotta do a compression test... I loosened all lines one by one at idle and 1, 2,3, and 5 squirt fuel pretty good. #4 is squirting barely any fuel. But I opened the lines on my OM617 1984 300D ( which runs perfect), and they spray also barely any ( WVO car, by the way).
So I guess I will do a compression test tomorrow, because I have a feeling it might be a bad cylinder, although there is no blowby at idle.