"....even tho the idle is backed off as far as possible."

There is no way to "back off" the idle on LH Fuel Injection. If you diddled with the throttle stop or link rod, you only added to the the problem. These things are pretty well covered in the Bentley 240 manual, which I think you'd get a lot of good from, with what you know already.

The idle is strictly controlled by the FI ECU. You adjustment may have thrown the Throttle Position Switch (TPS) off, so the ECU doesn't know what's going on. Or the IAC or TPS plugs may be loose, unplugged, or switched. (I think that last one can fry something in the ECU.)

And as Jorrell said, air getting sucked in after the AMM ("false air") is always a suspect. The O2 sensor will "see" it and tell the ECU the mix is too lean, so the ECU sends more fuel. More (false) air + more fuel = more rpms.
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Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

What do you mean by "backed of the idle"? Idle in 1989-93 240's is completely controlled by the computer, and not adjustable. The computer is "smart" enough to compensate for your adjustments. Whatever you changed, you should change back.

When changing major components, it's wise to unplug the battery (or just the 25 amp fuse behind the battery). This will clear the adaptive memory of the fuel and ignition computers and give you a proper baseline.

Otherwise, Jorrell's got the right idea.

-Ryan

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Athens, Ohio
1990 245 DL 133k M47, Cibié E-codes, Now with working wipers!
1991 745 GL 290k (Girlfriend-mobile)
Buckeye Volvo Club

First thought is a vacuum leak between the AMM and the intake side of the cylinder head. Another possibility is that your IAC is stuck and is allowing too much air into the engine at idle.

This smells like a vacuum leak to me, especially check the accordion hose between the AMM and the TB.

Hope that helps,

jorrell
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92 245 245K miles, IPD'd to the hilt, 06 XC70, 00 Eclipse custom Turbo setup...currently close to running again!