[T77911S]

just to make sure, the idle is adjusted with the big screw that goes into the side of the TB.

i dont know if your car has the throttle switch on the side but make sure it is adjusted properly. mine is not used and it was on the edge of making it idle at different settings.

vacuum line routing to the dist as mentioned.
if it is switched, the vacuum retard is run thru the thermo time valve then to the vac advance pot, it would raise the idle once it warms up.

i dont agree with how porsche did this. here is how and why i ran mine
i ran the vacuum retard to the themo time valve then to the retard pot.
porsche ran the vac advance to the thermo tinme valve (TTV). they did this so the advance would not kick in until the engine warms up. problem with this is if you go on boost when it is cold, there is not boost retard which i think is worse.
running it the way i did ups the idle a little more when cold.