It is not a throttle stop issue.
First,
Clean the throttle body. Water and a rag or your favorite spray cleaner. Doesn't really matter so long as the gunk is gone.
Take it for a drive and see if it's better.
If not,
Second,
Loosen the 2 bolts holding the throttle plate in place and back the throttle stop out so it's not touching. Open and close the throttle a couple times. When it goes back to the closed position look at the plate and make sure it's against the bore. You can give it a little force to close more or try to move the blade. If tight, tighten the bolts and move the stop screw so it just touches the lever.
Remove the battery cables and let the car think about what it's done to you for 15 minutes or so.
Put em back on and go for a drive.
Better?