For those who have been helping me figure out what is wrong with my car's idle (1991 745 Turbo) here is what my testing of the O2 sensor yielded:

--It cycles 6 times in 10 seconds between .9 and.1 volts, seldom .8 and .2 and never .7 and .3.
--It went right to .9 when I pinched off the fuel regulator vacuum hose and I immediately smelled gasoline and heavy exhaust (it was running very rich, I presume)
--I wanted to remove an intake vacuum hose and produce a lean situation but I wasn't sure what vacuum hose to remove from the intake manifold or throttle body. Please advise.

For those who haven't heard about this, I am trying to figure out why my car's idle is low in spite of a new TPS, IAC, temp sensor, RPM sensor...and a very careful and correct throttle switch adjustment, throttle body cleaning, etc. The idle hangs at about 600 or even lower, 500 in gear, and sometimes unexplainably surges up to as high as 1500. I haven't yet replaced the O2 sensor, but I have one and am going to because just after I got it the car had to have the head gasket replaced because of an internal leak. Knowing my luck it won't make a difference, but it is worth a try.

I appreciate the help and support.
--
Darius in Albany NY '86 744 GLE (172K); '91 745T (161K)