jmh
I had similar issue, couple of things I did was adjusted carbuerator float, make sure it is as per the recomended height and sometime it chokes the float needle. It has to move freely up and down so actually needle will not allow gas only when float bowl is full. In addition I had adjusted air screw. Secondly I redid my TDC with my distributor and seems like now truck idles without choke turned on. I still have somemore issues like vacuum not advancing and I have ordered new one for my truck.
Good luck
Ganesh
