Per the "101 Projects for your Porsche 911" book I have located the fuel mixture adjustment allen wrench hole (page 96) located between the fuel distributor and the large rubber boot above the engine and behind the airbox.
When I started the adjustment with a 4.5 mm allen wrench I swore I had it rotating counterclockwise to lean it out. I'm not so sure about the "clicks" I was supposed to feel.
I think I made a small improvement and leaned it out. The little fart-like mini backfires I was getting when I lifted off the gas seem to be minimized but they are still present.
Reference link - see "UPDATE":
http://forums.pelicanparts.com/showthread.php?threadid=184348&perpage=20&highlight=walker&pagenumber=2
Upon closer inspection and based on feel it looks like the allen hole is not a female allen but a stripped out screw hole. I just can't get any grip and feel rotation. I see no rotation using a flashlight.
To get a better grip I tried to use a slightly larger and longer allen wrench (non-metric) but it would not fit as the 5mm would not fit (too large) either.
I tried to get the 4.5mm allen wrench down in the hole deep with the engine running, but it seemed to slip down in the hole and the engine wanted to stall.
What the heck is going on?
The only allen wrench in my factory tool bag/pouch is very large.
I'm not sure what to do, please comment, I'll try to post a photo soon.