Stalling. This seems to be mentioned in other posts. I have the problem when decelerating to a stop. Has had extensive tune up with replacement of points, plugs, distributor cap, wires, timing, valve adjustment with little effect on performance.
Have you given the EGR system a checkout, your problem probably lies in the emissions controls.
Also look for vacuum leaks
check carb throttle plates for wear.for as mentioned above vac leaks.