Owning a 90- 300E with some 170.000 KM's on the charter, I sort of made it my mission to having it run smoothly. It does spin like a cat, but used to start very rough, worse when it had been left for an hour or so.
I read, and certainly appreciate, almost all the good advice in this forum, eliminating theories one by one.
Now I'm close... I really think i've gone a done it now..!
It starts first crank every time, and all I actually did the last time i had the hood up for a couple of hours, was to clean and lubricate the Idle Air Control Valve.
Ever since, I seem to get the right mixture when cranking, untill the CO sensor kicks in and closes the loop.
Anyhow, I'm happy for now, and thank all of you guys for your valuable contributions.