I have IAT Sensor code reading. I have replace MAF Sensor, both O2 sensors, idle air control sensor, plugs, wires, coils, I've also checked the continuity from the MAF sensor to the main computer and also have swapped out the computer with one from another truck that I have. So the computer is good.
I have two questions:
1) Is the IAT sensor built into the MAF sensor?
2)What else could I possibly be missing?
Thanks

 

Not sure on wiring for a 3.4, but if any of it is similar my 2.7's IAT appears to be wired into the same harness. IAT is linked to timing...maybe verify that your timing is squared away. Have you tried cleaning the senor itself?

 

IAT intake air temperature, its part of the MAF. Do you have an oiled air filter such as a k&n? if yes, throw it away and replace with stock. Then clean the oil off of your Maf. What year is the engine/ecu/truck? Is it the inline tube style maf? or the drop in style held by 2 screws? Do you have the ground from the engine harness properly grounded? Grab a scanner that can do "live data" and look to see what the computer is reading for the IAT, and compare it to the ECT. IF the Engine Coolant Temp sensor reads significantly different from the IAT when the truck is cold it could throw this code.