Ok gals and guys, I'm working on mom and dads '78 F250 400 2150 equipped pickup. They had a carb rebuilt to replace the worn out one they had. When it came back the throttle shaft would not return to idle when running, but would work fine engine off. I removed the throttle shaft and cleaned rust out of the pivot points. I reassembled everything and adjusted the linkage following a post by FMC400 and the specs from the Motorcraft kit I put in mine last fall. While that helped, there is still a little bit of a stick off idle. I lubed the throttle pedal and throttle shaft which seemed to help a little. It only sticks when there is vacuum. I don't work on carbs daily so a little help or advice would be appreciated.

 

I have seen this rebuilding some of my motorcraft carbs..

Nothing like trying to coast and that dam thing making you nail 1/2 throttle because its sticky

You need to take the carb off the intake, drain the gas and turn it upside down.

Take the butterfly valves out of the throat and clean the edges carefully to make sure there isn't any burrs or debris

Reinstall them but leave the 4small bolts 1/8 a turn loose( just enough so it isn't tight on the throttle shaft and pop the accelerator open then closed a few times so it will line the valves up with the throat then tighten them..

It fixes my sticky accelerator..

 

I did what you suggested and loosened the throttle plates to reseat them and tightened it all back down. I had already smoothed the edges when I had the shaft out before. Seems to have worked. Thank you.