Rough running on start up

[uteman]

E36 318iS M44 engine.;
Car has 215,000 km up and we have had it for 18 years.
Engine start when it has been sitting overnight results in it running rough for a minute or so.
After that first start it will start and run ok.
Idle could probably be a little smoother but it is certainly not what I would call rough.
Driving performance is equal to what it was when we purchased it.
New spark plugs, compression in each cylinder is great.
No sign of a head gasket issue ( I am an old mechanic)

Any clues folks??

[Eric93se]

Yes can remove and clean the idle control valve. Also smoke test it for vacuum leaks.

- - - Updated - - -

When you're out on the main road floor it a few times, hit redline, helps clean the valves. You can also get a bottle of Royal Purple complete fuel system cleaner.

[uteman]

Yes can remove and clean the idle control valve. Also smoke test it for vacuum leaks.

- - - Updated - - -

When you're out on the main road floor it a few times, hit redline, helps clean the valves. You can also get a bottle of Royal Purple complete fuel system cleaner.

ERIC: I dismantled the ICV then cleaned in ultrasonic cleaner.
Lots of carbon removed. Will see how it starts up tomorrow morning. Thanks for assisting.

[ed323i]

Perhaps try/swap the coil pack and high tension leads.. Perhaps those are old? Best to first inspect and then replace the leads. If that doesn't help, then the coil pack.
When cold and more humid, the chance of misfires/arcing are greater than when slightly warmed up. So it fits the symptoms.