Humm... Check the os that the new PCM has and compare it to your old os. I know the diesel guys have had problems with trying to flash tunes of different os's and that's one of the problems that they have when they do that. The EFILive guys said it's cuz there is sections in the os's that aren't visible to use that are different and they should stay with the same os there truck came with. Might have to do a full reflash to one of your old tunes, or have the dealer flash it with a update tune for your VIN.

 

I flashed it after EFI sent me a new License. Has the same OS and Tune I had on it before the swap.
Can I just throw a Custom OS at it without gettin into tuning right away?

 

Just disable/turn off the Custom sections..
Go COS5!!!

 

But was it a FULL flash with the fat red arrow?

For going to the custom OS, follow the tutorial and you will be fine with the tune you are running.

 

Yes it was a Full Flash. Updated OS and Tune both.
I'll try some things when i get my o2 fixed tomorrow.