Starts and dies before hitting 1500 rpm consistently

Only thing I've been able to find was the b2799 code for the immobiliser itself. Thought resetting it with my buddy's matco scanner then reprogramming it would have been able to fix it. Unfortunately still the same

 

Yea that's an ECM code but the Immobilizer ECU should also have a code stored in it I would think.

 

I'll take a look tomorrow and see what I can find out. What I do know is that this build shouldn't have been this difficult, just swap all electrical wiring and components off a running truck into a new cab and fire up

 

Update:
Finally caved and took it to toyota where they said the immobiliser and ecu weren't talking. Not a wiring issue thankfully. They are going to program a new master key as I only got 1 when I bought it and guess it was the spare. Then they'll reflash the immobiliser and ecu and that should solve this issue.
Thanks everyone for commenting a putting forward what you thought it would be!