1986 Ford E150 Van V8-302  5.0L

DTC's 12 and 13 are set.  IAC is not working.
Stalls at idle.

Have already replaced PCM and ISC motor.  Have
already checked all pins for continuity and shorts to ground.

Guess is that the problem is electrical, and not
mechanical. Any suggestions what to try next?

I am posting this for a friend who does not have
internet access. So I may not respond to help
right away as I have to do a go-between thing. But all help is
appreciated, even if I am slow in responding.

Jim S.