[wtm442]

Remove the carb from the intake manifold and see if problem disappears. That will rule out throttle cable and/or throttle plates hitting bottom carb gasket or intake manifold.

Then with the carb off the car you can play around with abandon and not dump a ton of gas into the engine. Could be quite a few things holding the throttle open, but I know one thing ... its DANGEROUS to drive it.

Once its off the manifold, clean everything with carb cleaner and a small acid brush. Disconnect the choke assembly first. The problem could be with the choke, but more likely the throttle linkage/fast idle cam. Or as Rick said, the throttle shaft is worn and the throttle plates hanging up in the bores.

If you have had 3 throttle springs on it for a long time, a worn throttle shaft could be the problem.

I'm assuming that it sticks with the air cleaner removed. Sorry, but I've seen some strange problems on carbs.