My 12a shutters/stumbles when I'm decelerating between 1000-2000 rpm in gear or out. It idles fine and pulls hard all the way up the tachometer from idle. What gives?

 

If it's a Stocker i.e. Rat's Nest still intact?
1st= Check your Coasting Valve
2nd= Check the Hose down by the Heat Exchanger. Due to the extreme heat in that area this Hose tends to go bad which will give you this type of sympton. Good Luck

sgieldon
steve

 

Motor mounts? U-joints? Check those. [Slim chance it will be those, but it never hurts to just look.]

 

Try adjusting your idle mixture just a little leaner.
(Shot in the dark.)