I got into AllData and got the proper diagrams. I was in the wrong spot. Everything put back together and did the recommended checks. I'm fairly confidant that the sensor and the wiring are just fine, but the ac voltage coming off the sensor is a little low.
I ran the car again, and saw some funny things on the scantool. When the engine started to act up, the upstream 02 sensor voltage went flat. Fuel trims flatlined as a result, and the spark advance bounced between 20° and -8°. Should I be chasing this 02 sensor instead? I'm not sure how I missed this before, I'm always staring at the fuel trims....

the engine doesnt normally shut down from a o2, you check maf, tps?

I've checked the TPS as well as I can without a scope. Seems accurate at the time the problem occurs. I am not sure how to go about checking the MAF, but I have "checked" it by replacing it with a used part. Didn't affect the situation. I can't help but be suspicious of the PCM, should I be?

i mean check it through the scanner, that verifies the wiring and pcm aspects of those readings. maf should be 4 or 5 gms/* at idle and go up quite a bit as the engine goes up and tps verify its 0 to whatever and is smooth when you move the throttle slowly

That'* the method I used to check the TPS. I'm not familiar with gms/*, but the engine idles with the MAF showing about .600 lb/m @ 700RPM and 200°. The MAF does respond appropriately when RPM are increased. I noticed that the problem begins before the O2 sensor shuts down. The O2 sensor shut down when I reached about 20% throttle in drive, and did so fairly consistantly. It went from operating normally to nothing, like it crossed some imaginary line. Timing was retarded a couple of times, but the problem persisted even when the timing moved up and stayed there. I have also installed a brand new MAP sensor that I borrowed from a project car that'* not currently using it. The codes will only come back when they feel like it. Shouldn't the O2 sensor have set a code for low voltage by now?

thats what i was thinking, maybe its bad. not sure i havent had any problem like that before

I have access to a PCM from a Chevy Venture. I haven't had to replace a PCM before, so please forgive my ignorance. Would that need to be reprogrammed? What determines when a PCM/ECM needs to be reprogrammed? Would I be able to avoid the issue if I used one from a similar Grand Am?

you cant just swap them, they have different programs for everything on the car and you cant swap one from the same car because of the security setup, it has to be relearned. you would have to have it changed by a dealer with the tech 2

depending on which type it is if you found one with exactly the same everything as yours it may work with the turning the key to run 3 times for ten minutes each

I have a different PCM, numbers match on the units. Came from an 01 Grand Am with the 3400. I'm in the process of trying to key it up using that method. It hasn't worked for me so far, and the security light isn't on. I'm having an issue getting this programmed. The dealer wants a non-refundable $88 "donation" to reprogram this thing. My old instructor has one, but I can't get the vehicle all the way up to the school. Wondering if I should just bite the bullet and take the whole car to the shop, or just have the PCM done at the dealer. I have never actually had to give up and bring a vehicle to the shop, I have no idea what that'll cost me (other than my pride of course).