IAT circuit problems

Hey guys. 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 Adhustment 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 Intermittant 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.
I greatly appreciate any responses. I am in a pinch right now, being unemployed, and I am forced to do all the repairs myself. I can't re-up my overdue registration in Nevada without a smog test, and they won't perform one until SES is off. Thanks in advance fellows

First off, DTC's never TELL you to replace parts. Just because a part is mentioned in a code description doesn't mean replace that part.

Saturn PCM's almost never fail. They are very well constructed. I know some guys with several Saturns and many back-up PCM's that they have never used. The engine won't run with a dead PCM anyway. In all my dealings with Saturns and other owners of Saturns I've never heard of a PCM actually failing.

Your transmission problem could be the beginnings of what is commonly referred to as "reverse slam disease". Google that and you will find out more about it.

As for your IAT circuit, there should always be a 5V reference with the key on. You have a break in the circuit somewhere between the sensor and the PCM. Time to start chasing wires. A pin-out diagram of the PCM will probably help. It will tell you which wire coming from the PCM is supplying the 5V reference.

Thanks Bro. Your help is much appreciated.