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2. IAC reset/min idle speed- This sets the throttle plate on the throttle body to a specific rpm. It should be set to 100-125 RPM below idle commanded in bin file. At ALDL connector you need to put a jumper between pins A and B of the connector. These are pins A9 (what/blk) and A12 (blk/wht) on the ECM. This puts the ECM into ALDL mode. Turn the key on (not start) and the IAC should drive completely closed. You will normally hear a buzzing from the IAC. If you have the TunerPro running up and running on your laptop, or a Scan Tool you should see the IAC went from 145 to 0. Now unplug the IAC connector. Turn the key off. Remove jumper. Start motor. If the idle is too low you may have to keep it running. On the front drivers side of the throttle body is the adjustment screw. It will probably be behind a silver plug. If so just use a drill bit slowly to drill a hole, not to deep as to damage the torx screw behind it, just enough to use a punch to grab it and remove it. Then use a #20 torx bit to adjust the idle speed to at least 100 rpm less then your warm idle speed in bin. If 600 then set to 500 rpm. You are looking for the lowest consistent idle your motor will do. When set, turn off motor and reconnect the IAC. I try to keep the IAC count to at least 10-20 with the motor warm and idling. Higher number are OK but more air pushing gas past throttle blades on TBI engines is better!
For your data how about checking what Pin the ALDL data is coming through on? Some cables can read both Pins but others need a specific pin. Code 12 and what your CEL is doing is a good thing!