This started in Carlisle.
Code 23- IAT lo- which means either open or broken circuit to the IAT

Replaced the sensor- old and new both read 1.66 ohms

Voltage at sensor always reads 5 volts
Replaced the harness that connects to the sensors.

Confirmed both positive and negative wires going from ECM to the sensor are in good shape. Read out to 0 ohms

Cleaned edge card of the ecm per manufacturer specs.
Used electronic cleaner to clean the actual white and black connectors to the ecm.
Verified solder joint of ham board to main board.

Check engine continues to go on and off while driving giving the same code.

Have I missed something? Can't think of anything else aside from running 2 new wires to the sensor.

Now I do use the same ground between my CTS and the IAT, could that in anyway effect the voltage? I wouldn't think so but I'm running out of ideas.

What do you mean by using the same ground between the cts & iat? Sometimes they are powered by the same 5volt wire, the heat in the air/coolant changes the resistance of the sensor. That is what the ecm is getting back from the sensor. Did you have the iac curcuit added when they set up your computer to run 8 injectors? Maybe try tapping on the ecm to see if it acts up.

The CTS and the MAT are both 2 wire sensors not 1.

The ground wire that come from the ecm connects to both sensors. (shared ground)

I would suggest something as simple as disconnecting your negative terminal on the battery. I haven't had much electrical troubleshooting so I'm currently not very knowledgeable on this source. Try running those new wires then. Seems with all that you've changed things should be going good.