Need help with hard start

I bought two Tacomas, one with a damaged front end, the other a freshwater flood truck.

Used body parts from the flood truck to finish off and make one good truck. It is fully driveable.

Back to the flood truck. Simply put - I only get spark for about 3 or 4 rotations, then the spark stops even if you hold key and continue starting. I do get a couple of combustion pulses along with the spark, then nothing.

I'm using the ECM from truck 1. Already established flood ECM is innoperable. No spark no matter what happens.

Verified immoblizer system by removing transponder ring from column and hang truck 1 key in it while using flood key to start truck. Immobilizer system continued to flash. Reassembled and no immobilizer indicator.
Things that have been addressed already:

Tank drained physically and also at return line after rails. Fuel pump is working. Fresh fuel added.

Oil drained and refilled

Throttle body is opening and closing normally.

Compression 'feel' good.

Spark is present using light tester that connects between plug coil and plug, but only for a few rotations.

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I don't have a scanner to read the data. Unable to verify if I'm getting crank or cam signals, though I could check resistance per manual.

Will ecm spark discontinue if it doesn't read crank or cam signals? I can pull these sensors off a third truck if necessary. Any other ideas?

 

Found this in the manual:
"When the transponder key ECU detects that the unlock
warning switch is ON, the ECU provides current to the
transponder key coil and produces a faint electric wave.
A transponder chip in the key grip receives the wave.
Upon receiving the wave, the transponder chip outputs a
key ID code signal. The transponder key coil receives
this signal, the transponder key amplifier amplifies it, and
then the signal is transmitted to the transponder key
ECU. The transponder key ECU matches the key's ID
code with the vehicle's ID code, which was previously
registered in the transponder key ECU. If the ID codes
match, the transponder key ECU turns OFF the security
indicator. Then when the ignition key cylinder is turned,
the code match results are sent through the transponder
key ECU to the ECM. After the identification results show
that the key's ID code matches the vehicle's ID code and
the transponder key ECU has confirmed their match, the
immobiliser system is canceled and the engine starting
controls (fuel injection control and ignition control) enter
standby mode"

So am I correct to say that all 4 (key, amplifier, ECU, ECM) all have to be programmed together? What I am experiencing is the ECU says "yes" but the ECM is saying "no"?