Well, after posting, I did some more scouring of the web to see if anyone else has had this issue, and I found a post on Renntech (
Squeak / chirp at low RPM - AOS related? - 986 Series (Boxster, Boxster S) - RennTech.org Forums) describing the same problem which turned out to be a loose spark plug!
Last weekend, I actually replaced one of the spark plug tubes and o-rings because of a small oil leak from it. Could this really be the culprit?? If oil got onto the actual spark plug, should it be replaced or can I simply take it out, clean everything real well and then replace and torque to spec? could this also cause the rough idle?
man if it is simply a loose spark plug...