have you tried putting the old TB back on and see if it will start that way?
The TB you picked up could be bad, unless you grabbed a new one? do you have VAG-COM or know of anyone with VAG-COM? maybe they can come scan your car and see whats happening..
do you have any CEL's?
it is possible the pedal could be bad as well.. but your kind of shooting in the dark without codes of any sort...
have you attempted to clean the Tb?? like take apart and clean??
once you pull a TB off or clean one you need to Re-align the TB with VAG.. not saying this is your problem.. but it should be done when anything is done to the TB