Hey Gryphon - Another possible reason for your idle issue may be the WUR (Warm-Up Regulator). It is responsible for setting your fuel pressure at the air/fuel control arm in the fuel control unit while the engine passes through a cold start to a warm engine.
One other comment - To perform the pressure tests needed to diagnose most CIS injection problems you must (buy or borrow) have the proper adapters, test gauge, shut-off valve and fuel line setup. J.C. Whitney used to carry a nice very reasonably priced unit. They are well worth the purchase if you intend to maintain an early Bosch CIS car.
Here is one of the many discussions on the WUR - although normally factory set, they can be adjusted to tweak the final pressure setting. The Bosch CIS components and operating principle is the same no matter being installed on a Saab, BMW, Mercedes, Porsche, etc....
Pelican Technical Article: 911 Warm-Up Regulator Adjustability
Keep Us Posted on your progress, Michael