these tb's are known for this, some have problems some don't, i don't know why this happens but it has something to do with electronic engine control. i have one on my car and don't have a problem. try returning it for another one than see what happens.
Take it off and return it if you can, or sell it. The stock TB is more than adequate for an n/a car. I've seen them dynoed myself and they come up with a whopping 2hp gain. For all the trouble people have with them, they're not worth it. If it was working, it wouldn't hurt anything to leave it on, but since it's not working, it's not even worth the hassle.
The car just stopps. No throttle responce, and the wrench light & enging light come on. It usually goes ayay when I restart the car. But It only happens when I'm driveing.
With this new drive by wire, tb swapping could be touchy. I would think porting or cleaning up the stock tb might be a better choice for a little added throttle response.
I have the bbk 62 with zero problems, you might try this to see if it is the tps sensor http://www.americanmuscle.com/bbk-trouble-shoot.html
After reading that article, it really seems like that might be your problem, good luck!
I had a similar problem with my first BBK TB. I tore it apart and found that it had a sticky plunger so the spring couldn't fully return it to the closed position. I returned it and got a new one and this one works fine. I agree that the HP difference is minimal.