Not a carburetor, but possibly carbon buildup within the throttle body, causing the throttle plate and stick when you press onto the accelerator. You can easily check it by pulling the intake off of the throttle body and open up the plate to see if it sticks. If it does, then you can either clean it yourself or pay a mechanic to do it for you.

Also, I would go to a different dealer if I were you because if the dealer thinks the TL has a carburetor, then the dealer does not know jack.