1996 Ford F 350 has a connector under the dash that I'm using. I haven't looked for a connector under the hood. Your question got me researching and I found that there were some F 350 7.5L California trucks that were equipped with OBD II. Also found that some had the OBD II connector, like mine, but don't have OBD II capability. WTH Ford?
Addtl testing. Drove with MAF sensor disconnected. Started great, ran rough at low speed, fine at speed. Real time scanner data said that Bank 2 was rich and that MAF sensor had low flow (as expected since it was disconnected). Came home, truck still running, plugged in MAF. No change. Unplugged, no change. Turned off truck. Plugged in. Started and it barely loped and eventually stalled - no response to throttle. Unplugged MAF, truck started fine but idled rough.
Installed original MAF. Same results.
So I'm assuming with MAF plugged in, it is telling engine to lean out to the maximum. With MAF unplugged, engine is told to run rich. But if the MAF isn't faulty, then what is it?
Yes some Cali trucks were OBD ll, 1997 I believe.
Find the EEC IV connector under the hood and see if you can pull codes.
There was a Federal exemption for trucks over 8,500 gvw.
When you remove the MAF the ECM goes into limp in mode.
I have concerns with the ecm.