Haven't touched the distributor since I started playing with the truck again. (almost 2 years) I went through the steps you described but the mechanic has touched it since then. I thought he had the idle too high and the mixture too rich so I backed both down. Right now the idle is at 900-1000 rpm, which still seems high but it runs better than a lower setting. When I had the linkage off, to do carb adjustments, I also adjusted it's geometry to better clear the manifolds.
