Will not stay running when put into drive but will idle and run in reverse? 1 DTC Code intake air temp sensor, replaced still does the same. Whats the problem? PCM?

Many issues will not set a code so start with basic troubleshooting. Is fuel pressure correct? Is EGR dirty or sticking open? Is IAC dirty or sticking? Is compression correct? Bad coolant temp sensor, bad O2 sensor, clogged exhaust or converter all can cause this, even a bad vacuum leak!

coolant temp sensor and intake air temp sensor would be the next to check.intake air temp sensor is in the air intake tunnel between TB air air box. when running is there a DTC? by disconnecting the coolant temp sensor you put the ecm values at default try that if it corrects your issue replace it.(it will turn your check engine light on but you can clear later by disconnecting battery)

2506 PCM/ECM Power input signal range/performance
110 IAT Intake Air Temp sensor 1 circuit
104 MAP/ Baro sensor low input
You probably did do some damage by not isolating the engine and controls out before the repairs/mods were started.

Dont clean your throttle body yet..........Theres an idle air control valve{ black round top about the size of a 50cent piece} on the back of the throttle body, cleaners will ruin it. It mounts with 2 screws facing the back of the motor. This is what controls your idle.........

Duplicate question.

DTC P0171 - System Too Lean (Bank 1)
Basically this means that an oxygen sensor in bank 1 detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1.

Note: This DTC is very similar to P0174, and in fact your vehicle may show both codes at the same time.

According woth your previous tasks, inspect all vacuum and PCV hoses, replace if necessary.

the idle is controlled by many different sensors on a computerized vehicle, some are oxygen sencor, water temp sensor or map sensor,, you really need to have the car put on a computer scanner. This in a long run will save you money by fixing whats wrong instead of just changing parts that may not fix it.

The engine coolant temp sensor affects cold starts. It sets up the fuel for cold idle. There is another sensor called the maf or mass air flow sensor. It is located in a metal tube section of the intake ducting. It is a flat sensor with a metal strip. It measures the density and velocity of the air going to the engine and talks to the computer to allow the fuel in the amount needed for proper air/fuel ratio. This sensor can be cleaned with CRCelectrical cleaner from the parts store. Use only this spray to clean the sensor. Do not rub, brush or touch the sensor. It is vry expensive to replace, so just spray wash it the best you can with the CRC Make sure the air cleaner is clean.
Good Luck, _Ned_

I had the same problem - replace the intake air temp sensor and the idle air control valve. This should take care of it, while you are at it you should change the camshaft positioning sensor - that will go next, then sell it, when they run they run good, when they break it is always everthing but what it should be. LOL that is my opinion though!!

You failed to give the model year which could have an influence on the accuracy of this answer:

" IAT Sensor 1 Circuit High Input"

Stolen from another forum:

"Intake Air Temperature (IAT) Sensor

The intake air temperature sensor (IAT sensor) changes resistance in response to intake air temperature. The IAT sensor resistance decreases as the surrounding air temperature increases. This provides a signal to the PCM indicating temperature of the incoming intake air."