A little background...
What ECM are you using? Stock tune or what?
What wiring harness?
Are you running a supercharger?
Reason I ask is the baro sensor is typically for a supercharger application...
As to the P0641, sounds like you lost 5 volt reference to a sensor(s). Typically on the sensors pin 1 is the 5v reference. Usually are 1 or 2 circuits with 5v signals.
You don't really need to start your car to check the TB. Just turn to on. Watch the blade, if it responds slightly(indexes itself) then you know it is getting some signal. You can press the accelerator pedal and the blade should respond to input...
If you can't find the 5v reference signal, check all the sensors, each one should have it there. You may have to trace wiring back to ECM.
T,
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