You may have to adjust the vacuum idle regulator (driver side of carb).
Unplug the hose and set the idle to 2000rpm (at lot) with the bold on the end.
Then reattach the hose and adjust the spring tension with the big nut.
With an automatic transmission there should be a 1mm between he bold and the linkage, if you have an airco, switch it on and adjust the spring until the car idles well.

An other thing to look at is the ignition. Set the points to 39-41 degrees, this is very important. One degree off and the car will not run as it should.