That is the throttle check valve. It is designed to allow the throttle to ease back instead of snapping back when you suddenly let off the accelerator pedal to prevent the engine from stalling. It will not cause the gas pedal to physically stick but can cause the throttle relay to carb throttle rod to be pushed out causing high idle if the actuator diaphragm is busted or the adjustment screw is set too far out. I would 1st apply vacuum to the check valve and see if it holds vacuum. If not it needs to be replaced. (I have good tested ones for sale if you need one). If it is working, I would try adjusting it per the adjustment procedures in the 1963 Shop Manual on page 10-33 section 26.f.
As physically sticking gas (accelerator pedal), it may be a weak throttle return spring or corroded pivot base. The bases on these often corroded over 50+ years and again I have nice gas pedals if you need one. To test the pivot base, disconnect the linkage from the throttle check valve and relay assembly on fire wall, and move pedal up and down with your hand. It should move freely with not much resistance. A shot of WD 40 may help if it is just sort of sticking.
If you need the check valve, or complete relay assembly, throttle return spring, or the gas pedal email me at firstname.lastname@example.org.
Just to add, early in the 1964 Cadillac production run, they switch from the vacuum controlled throttle check valve to a spring and orifice dash pot that does not require vacuum. It is a simple spring orifice that lets the accelerator ease back without the use of vacuum with was sometimes problematic under certain low-vacuum situations (and of course when one was busted!). I also have the 64 style dash post assembly that can be used on a 63. You just need to disconnect & plug the vacuum line that would have run to the vacuum throttle check valve. Click Here to see the November Serviceman Bulletin showing the new dash pot setup.
this sounds like a dangerous situation to be in
if i am understand that this happens when you are driving the car suddenly
this happened to my cousins car
he had a broken motor mount that would cause the engine to shift and in doing so cause the throttle linkage to pull the cars carb wide open and charge foward
he would have to turn the key off to get some control of the car
not exactly sure this is what you are talking about here but could be similar to the info you posted
So where would the return spring be located and what part might be corroded exactly on the base of the gas peddle or on the carburetor where the linkages are on the carb, they are free thanks!
The throttle return springs attaches to the throttle rod where it goes through the carb throttle plate on the front; and attaches to a bracket that is attached to rear intake bolt. Any spring with the correct tension will work.
The gas pedal pivot is on the very bottom. See picture below of a very nice gas pedal assembly I have for sale which you can see by Clicking Here:
Awesome just what I wanted to know I appreciate the help I'll have him check for these things,..... weird tho both of our cars didnt have this spring when we bought them I kinda figured mine wouldn't due to someone already being in their but his hasn't been touched in over 25 years.. maybe someone ran it without the spring or something and we never noticed a spring was supposed to be their