I'm back from Vald'Isere ready to face the music
. Today I replaced the alternator with a 150A model, upgrading the wiring to 2 4AWG cables etc. The underlying problem still seeems to be there although it didn't cut out tonight. When engaging electrical components the RPMs only deflect slightly, not as bad as before. However the idling is still inconsistent. Sometimes at 600, then 500, then later 600 again etc. Very strange. Tomorrow I'll grap an OVP and replace that. It could perhaps be the battery not holding charge as Robby suggested although I'd have thought that with the car running the alternator, or at least a 150A one, would take care of everything.
Today I tried an updated OVP, p/n end 37 45 & also a different ICV. Both didn't make a difference. However I noticed that when it is idling slowly, if it is given 3000RPM or so for a few seconds it will then rest at a higher idle and be okay for a while. I'm going to remove the air cleaner assembly & clean out the part below it now in case all that crud is causing a problem. After revving it idles perhaps a little too high, then slows down bit-by-bit suggesting something is sticking perhaps.