[automan9482]

Thanks Brian. I will follow your advice and check those things out.
I set the timing per the factory manual, with the vacuum disconnected at 0 degrees TDC. All the manual says beyond that is "check timing further at 12 degrees BTDC." It didn't call out a procedure for that, but I will check it at 12 degrees with the vacuum connected.
I will also check out the other things you suggested. I am leaning towards a carburetor issue, just because it is a little hiccup-y when its cold, and it has had the persistent minor backfire. Also it didn't occur to me before, but I believe there was a backfire in the carburetor at one point. I had changed the air filter, and several months ago with the air cleaner off I noticed a part of the air filter had melted. I will check it out, and hopefully find A good cause for the problem.