STFT's freezing up, cracker showing but not actually operating

[blownbluez06]

I've disabled LTFT's and LTIT's. I'm fighting this car trying to add airflow when it's moving. I've added both cracker and rolling idle air and when the car's rolling, it shows the cracker as it should, but the throttle position doesn't ever change as a result. I've gone as far as adding 2lbs prove it's not working. Also, I've heard about the E67 and E38 having an issue where the fuel trims stop working momentarily due to misfires in the background, but this is not the same kind of issue. In this case, the fuel trims are freezing at whatever value they're at and they stop moving at all, negative or positive. I haven't discovered any correlation between anything causing it. The freezing trims appears to be random.
This is in a 2001 C5 with a 3-bar OS

[blownbluez06]

So I've flashed a stock tune in and started from there, then pushed a 2002 OS into it and neither helped. There is a serial data bus between the PCM and TAC and I proved good continuity but have no ability to prove there is communication. I'll assume there would be a code thrown if there was a full breakdown in comms, of course I could check other functions that require that serial link to function like cruise control to prove it. Everything is finally working after isolating the trouble completely and replacing the defective parts.