tlc488

My 1992 400 SE is giving me quite some problems . I have recently fixed the crank shaft sensor (due to rough idling and dying down) the problem went away but shortly after, I am now having idling problems. The rough idling only occurs in park and it is very subtle after a lot of driving. Funny thing Is the car drives perfect. The rough idle is the only problem. I got a diognsotic performed at MB dealership but they couldn't find the problem.please help