SC/SL/SW :: SES Light Came On / Code Was P0112 - IAT Circuit?

I have a 1996 Saturn SL1. The SES light came on and I scanned it. First the only code was p0112. I replaced the IAT sensor. The light remained on, scanned again and the code told me to replace the Idle Adjustment valva. I replaced that, SES was still on. Scanned for the third time and it told me to replace the sensor in the exhaust. Replaced that, SES still was on. Scanned and got code for Intermittent Voltage problem with IAT. Drove 60 miles (as recommended) and that code and SES light went off for a few miles and then the original coded p0112 came back on. Pulling my freakin' hair out! Was told to check voltage at the connector cap of IAT. I did and found continuity to ground but no input signal voltage (5v I was told). Stripped the wires back behind the connector cap and still have no voltage from the PCM. My questions are:

1. When does the PCM send the 5v signal voltage to the IAT? When you start the car or later in the drive cycle?
2. My car has shifted badly for a while (small hitch when shifting into reverse after car is warmed up, not when cold). I found a thread that told that the 5v signal circuit could also be utilized by other sensors, one of which affects the transmission shifting.
3. Could the PCM be out? Would the car still run if it was out.