carb sticks wide open on '67 289 2V

[DADS67]

Just bought a '67 2+2 with 289 2V. When the accelerator is pushed to the floor, it sticks wide open! When I manually open the the throttle, it gets to a certain point and then "snaps" to wide open and stays there.
I have to pull the linkage back. In the car, the only thing to do is shut of the ignition. It restarts ok.
Is this a return spring problem? There is a spring from the 90 degree bend in the linkage to the carb. There is another spring (like a clock spring) on the throttle shaft. I guess I'm lucky is a stick shift...gets kinda freaky when you push in the clutch and the engine red-lines.

Thanks for any ideas.