Alright folks... I've done it and I've gone crazy. What's it going to be, IDM or PCM?

Back story and information:

Ford 7.3L F350 Dually Super Crew Long Bed Lariat LE

I bought another truck to flip for a few bucks and it had a check engine light. Seller told me it was a bad IDM after some faulty wiring blew it up. They also showed me the receipts that show everything that would have fixed it (replaced UVCH and an injector.)

So, I swap out the good IDM from my truck to do a quick check, pass smog, register it then get a replacement IDM for the vehicle later. Check engine light still remained even after clearing codes (but the engine ran fine) so I was like OK whatever. Put my old IDM back into my truck.

Now my truck is running funny. Buzz tests and everything else showed it as essentially an unplugged injector #3. Tested the wiring from the IDM harness and everything was fine except it showed injector 3 as open. So I start chasing down the break. Everything checked fine and even me taking a paperclip to the IDM harness and testing ohms on injector #3 worked just fine when initially it didn't. That was weird.

Buzz tested the injectors again, same issue, so I plugged injector 1's plug into injector 3. Injector 3 worked beautifully (obviously the others didn't because they weren't plugged in.)

So now that I know there's no break anywhere, is it the PCM or IDM? Any easy way to test either? Reason I say PCM is because that's what ForScan says could be one reason for the issue, so I'm just throwing it out there.