Now to me it would seem a lot easier and more reliable to include a line pressure sensor and allow the TCU to 'learn' new values. Then again I'm not an engineer or programmer.
Maybe you know something that I'm missing, but a 'duty cycle' valve, to me anyway, means that it regulates pressure by frequency of cycles. Being a solenoid it's either on or off. Is it that you're seeing a voltage change as an indication of cycling rate changes? I guess this is all moot as your problems are solved, I just found it interesting.
Now I can see why you were interested in checking your TPS. I kinda came in at the end of it and assumed you were in it for an engine problem.
Beav