Thanks Steve.
Here is the update.
No rain here yet, so I removed the ICV. Sprayed (thru hose connections) the crap out of it with Brake-Carburetor cleaner.
Let it sit for a while, shaked it and removed whatever carbon deposits (not much) came out with the cleaner. Repeated procedure until the solvent was coming out the same color it went in. Put it back in, idles marginally better. Spray some of the stuff all around hoses. No change of idle (no vacuum leaks???). Idles fine. (600-650 RPM normal operating temp). Duty cyles 28-39%.
Rev. the engine to 2000 RPM steady, duty cycle 45-50.6%.
Go for a drive, find nice strech, gas it to 5000 RPM several times good response.
Stop, park. No dancing idle yet (500 to 900 RPM).
Remove 02 sensor, duty cycle rock steady at 50.2%. Plug it back in. Duty cycle 29-39%. (O2 sensor obviously working)
Start playing with idle control mixture screw. Turn, turn.. duty cycle at idle 39-49%, at 2000 RPM 50-60%.
For the life of me I can not get it to be 50% +/- 5% at both idle and 2000 RPM. Still idle appears fine.
Are the values I am getting good enough?

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1999 Porsche 996 Carrera Convertible
1994 420E - SOLD
1986 300E - SOLD, what a car
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