Porsche Repair: 1979 Porsche 930 Idle Problem, porsche mechanic, air hoses

Question
I have an idle problem with my 1979 porsche 930. The idle bounces from 950 rpm to 1500 rpm at operating temperature. It seems to clear up when I drive the car hard. When I park the car, the idle will be smoothe for about 10 min but then it gets rough until again I drive the car hard again. I've replaced all of the air hoses, clamps, I've put in a new warm up regulator, replaced the cold start valve, replaced the thermal time switch, replaced the fuel injectors, spark plugs, ignition components, but I have not replaced the auxiliary air regulator. I've had this part tested by a porsche mechanic, who ended up telling me that it seems like it's working. Could this be the cause? I've read a tech tip on this part that said "that a defective unit causes hard idle when the engine is cold," but does this apply to when the engine is hot? Could you help me?  

Answer
Hi David.  I'd say that the tech tip was only half right...it will also cause idle problems when hot.

I haven't been nose deep into a 911 engine bay on a 930, so the question is can you get to the AAR?  If you can get to it and if there are only  hoses running into and out of it...can you take it out of the line for a test...just replace it with some appropriate tubing.  Drive the car a bit and see if there is a difference.  The AAR, which is a valve, can be sticking.

Let me know what you find by using the follow-up feature of All-experts.

Dave