89 240sx surging idle

[Edub1]

Idle goes from normal to 1500 and back. I have traced the problem to the AAC letting in too much air. I know this by pinching the hose.

I took it off and cleaned it and cleaned the IACV - no change. Solenoid seems to work but adjustment screw has no affect on idle.

Ran ECU diagnostic, showed bad IAT sensor - don't know if this matters.

I should also mention that this only happens when the car is warm and has been running for a while. Plus, my wide band O2 reads rich when the idle drops and 16:1 when it surges.

Please help.
Modified by Edub1 at 4:39 PM 3/31/2007

[rogoman]

Couldn't find IAT sensor in the FSM; maybe you mispelled it; wnat is the actual ECU fault code?

[Edub1]

Found problem - bad ECU
Modified by Edub1 at 8:00 PM 4/2/2007