I have an '87 300e. when I turn the key to start it, it does not start the first time, but it always starts the second time. It will start the first time if I let the starter run for 10 seconds or so, but I should'nt need to do this. (it seems to do this no matter if the engine is cold or warm. It does not do this when the engine is warm and has been on within the last 10 minutes).

Could this be the cold start valve?

I also seem to notice a bit of a rough idle at the trafic lights, but the car drives fine. (not a misfire, but a bit rough)

Any help would be appreciated.