Some good suggestions here, as always. I have seen a lot of these older F series pickups with various PCM issues due to grounding issues at the passenger side firewall. May help to overlay 12v and ground to the PCM to see if that helps. Also, did you install a rebuilt/aftermarket PCM, a used unit, or a unit out of a known good truck? Have definitely had bad reman units out of the box

Andrew Alves
Technician
Red River Ford
Durant, Oklahoma, USA