Motronic doesn't like and frankly...

[Morgenster]

Thanks for the input guys.
This weekend I'm going to test every sensor I can get my hands on. I'll be borrowing a multimeter from work.

As for the TPS ohm-readings: TPS on M50 is a pot-sensor and should read 1k ohms at fully closed to 4k ohms fully open according to Bentley, but they don't specify any tolerances. I'll be testing it again anyway.

Now that the weather is improving the symptoms seem to get better again.

[BillionPa]

+- 5% is your "safe bet" tolerance, if the multimiter has been adjusted properly.

[Morgenster]

Just posting to follow up so people can refer to this:
My TPS resistance at fully closed is somewhere around 1,7k ohms.
I adjusted the little screw that blocks closure of the throttle butterfly (top left of throttle body) and it took some time to adjust but it worked.
I also found out that the margin on the TPS is 1-2k ohm for idle through a specialised software my mechanic showed me.
Cold starts are fine now.

[Barney Paull-Edwards]

It may help in future to be able to find out which plug/lead is u/s.Buy a snap-on or similar heat detector(looks like a plastic starting pistol),they are about $60 here(UK) but the best diagnostic tool ever.Just point at manifold and it will show the duff one,also good for all sorts of other troubles like wiring potential faults/sword defects etc.I have a twin (8) plug headed BM motor and it`s saved me a fortune in plugs and leads.