what is the voltage at with the key in the on postion? It doesn't sound like it's calibrated properly. are you able to move the throttle body plate by hand with little ease a few times and then re-check the voltage? I would simply use a digital voltmeter first to verify the voltage, adjust if necessary and then cycle the key three times to do a "soft reset" and start the car.
You should be able to move the throttle body plate with your finger, and it will close on its own. If it takes excessive or considerable force to open the plate with your finger, something is definitely wrong. There will be some spring tension but not enough to make it too hard to open manually. Maybe you should remove the actuator motor and re-seat the spring and calibrate it again. The voltage should be adjusted to match 100% to what the stock tb had, or you're asking for problems.
It's important to check the voltage, then manually move the throttle plate and check it again to make sure that the tb plate closes fully and goes back again to the exact voltage.. If you just install the throttle body and adjust the voltage without working the throttle body plates it won't be exact. I only say this because when I installed the bbk tb, i checked the voltage, thought it was set then worked the throttle body plate and
when it closed it it was drastically off and had to adjust it again.
Borrowing another tb is useless because every engine has a different tps voltage from the factory. Why do you not have your original throttle body? You should always keep stuff like that even if you don't intend to use it. I can't remember the exact number for mine but I think it was 1.21, and I think the range is anywhere from 1.13-1.27 but don't quote me