Set your idle screw by backing it out until you can slip a .010" feeler gauge between the end of the screw and the stop plate. Tighten screw until you can feel a little tension when you move the gauge. Remove the gauge and turn the screw in another 1 1/2 turns.
The throttle adjustment screw is down by where the throttle cable connects to the throttle body.
It should be able to idle at this point. If it doesn't, it sounds like the IAB is probably bad or not hooked up correctly (or electrical problem as you potentinally may have).
Do you have that big ground strap hooked up to the engine block? Ground wire going from battery to block?
Have you pulled the codes from the computer to see what it may be complaining about?
Thanks for starting the new topic.
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351W 89 Mustang GT Convertible