This may be due to 2 reasons.
One is the fact that the throttle body bore has a groove worn into it due to a worn throttle shaft bearing. This cannot be fixed as you will have to purchase and replace the throttle body.
The other could be a frayed or binding accelerator cable.
how do you fix timing on wipers 2000 buick regal
Remove the float from the Regal. inspect the float for leaks, then check the spring and needle valve as it could be stuck. If all parts are ok then the parts need cleaning as they are sticking.
Wandering fuel gauge on a 2003 regal
With a very big hammer
quick fix on youtube.com with video
try checking the gasket around the intake that should fix it
How to fix heater in Buick there is cool air ,fan is work .but no warm air
WD-40
you will need to replace the throttle cable, and while you are at it check the return spring.
You might have to take the car to a certified speedometer repair shop
Check the cable that connect the accelerator pedal to carb., may have slipped out of retainer.
How do you fix 1998 buick regal GS heated seat, on driverside , Right side still heats I need book on seats from the people that made the seats.