I know that the idle screw is factory set but some bozo before me cranked up the screw because the IAC (air bypass valve) wasn't working correctly. I would like to know the procedure to set the throttle plate screw correctly, can't seem to find the info anywhere.
I also need to know the desired idle speed, it doesn't say anything about it on my engine compartment sticker.

Thanks, Jim

 

I don't know about a throttle plate screw, but I have adjusted the screw on the throttle linkage to adjust the idle on my wife's '92 Aerostar 3.0. I think I have it set around 700 rpm. IIRC it seems when the air conditioner comes on it automatically adjusts the idle to stay where it is set.

 

Ok, was out in the Aerostar today. Here is what I observed:

Idle was 750 with air on and in gear.
Idle was 850 with air on and in neutral.
Idle was 850 in gear and air off.
Idle was 1050 in neutral with air off.

Anyway, set the idle so it is aroun 700 with the air on in gear and you should be fine.

 

you want to unhook the idle air bypass valve then crank her up and with it under no load back the screw out slowly untill it stumbles down and dies. hook the idle air bypass valve back up clear the ece and your idle will be ecu controlled. that is the way it is set from the factory and anytime something cause it to be messed with like bozo lol. either way that is the way that a dealership would set it. if it won't idle that way or dies even after the relearn then you have a problem elsewhere.