My 103 engine sometimes stumbled and stuttered badly on cold start, but I could clear it's throat with a push on the pedal, so I ignored it for awhile. Then the warm idle got just a bit rough.
Techron didn't help, so about 1 easy hour and $120 later I had new injectors, and both problems went away. Great thing about these mechanical injectors; they are relatively cheap and a piece of cake to install on the 103.

S-Class Guru