I had this problem about a year ago in my 84'.  A lot of people on the list
said to remove the Cable and wd-40 the tube and all that nice stuff.  I
tried a new return spring but that did not work either.  I finally figured
out that there was a build up of ice and slush and stuff in the carpet
around the pedal and that was making the pedal stick in certain places.  I
just took a razor blade or scissors or something like that and just cut away
some of the carpet around the pedal so the ice and slush wouldn't build up
right around the pedal like it was doing and it has worked fine ever since.
You could try that and maybe it will help.  That is my experience.  Hope it
helps.
 Tim Vogelin