I have been on a wild goose chase to try to figure out why my car's (745 Turbo, 162k miles)idle is too low (around 600 under load, 700-750 in Park or Neutral), and when the idle is low and car fully warmed up, the oil pressure light goes on. Maybe some of you have read my many previous posts trying to solve this annoying problem. I would really love some help solving this as it I have become somewhat obsessed with it. BTW the car never stalls.

I have replaced (or had replaced)
--02 sensor
--coolant temp sensor
--throttle position switch (yes, it is correctly adjusted)
--rpm sensor (replaced by seller when I purchased car in Arpil 03)
--Idle Air Control valve
--fuel pressure regulator
--throttle body cleaned
--vacuum hoses checked (no leaks, all clear)
--crankcase checked for negative pressure (good)
--oil breather box checked (it is open,oil pours down into it easily)
--clamped off the hose to the idle air valve and it caused the idle to drop to about 300 (didn't stall till I removed the plastic clamp), which means the IAC is working

None of these attempts to fix the problem has worked, though the idle in Park and Neutral seems closer to normal than it did (around 750). But under load, in Drive or Reverse, and with the a/c on, the idle dips to 500 then recovers to 600.

I am at the point where I am ready to take the car to the local Volvo dealer to have them work their magic and diagnose this very persistent problem. The guy who runs the service dept is very helpful but suggested I just live with this until (and if) it gets worse. (BTW, oil pressure is fine at idle, it was checked by my indy mechanic.)

If anyone has any ideas about what might work, I would deeply appreciate the help.

Thanks everyone.
--
Darius in Albany NY '86 744 GLE (172K); '91 745T (161K)