Ok, I had to get out there today and verify the timing to begin with. It appears that the spark advance hack doesn't show the base timing when you are following the procedure to set the timing. In any case, the base timing is at 0 degrees.
Next up was upping the BPW in the bin from 135 to 144 and upping the IAC CL Desired idle table. I added another 50 rpm across the table.
Now, if anyone can explain to me why setting the idle rpm with the throttle stop screw and having the IAC disconnected does anything, I'd appreciate it, because it sure seems to me that the throttle adjustment and IAC count is more important while while in gear.
In other words, when I disconnected the IAC and adjusted the idle rpm to 100 below the desired rpm, I ended up having to readjust the throttle plate with the truck in gear to get IAC counts to about 15.
So, why the readjust? Am I doing something wrong?
The only thing I can think of is that once I find where this engine wants to idle, that once the idle rpm is adjusted with the IAC disconnected, that when it's reconnected and in gear, it should fall into place without any further adjustment.