Sometimes, the plugs or wires are a problem, in a case like this, and they are the easiest things to check. What I'd do, is change the plugs, just out of hand; don't try to second guess them. Or, at least check the resistance on all of them and make sure they are all pretty close to each other; large differences could cause a problem. Same with the plug wires; they have a spec for resistance, and should be within the spec, and pretty close to the same on all wires. There will be a slight difference because of the relative length of each wire, but I think you can get my drift. Next is the distributor cap and rotor, and if you run points and condenser, examine them all really well, or just replace them with new, and check the new stuff well, too. With the Torker manifold, I believe you can see down the runners from the carb base with a light and a small inspection mirror; lift the carb, and take a look. If you have access to a borescope, use that, and look all the way to the valves. Sometimes, surprises hide in the dangdest places. The carb may be unbalanced, or there might be a stuck needle or clogged jet, or a bleeder port thats not "bleeding" right. Did you recently overhaul the carb? Get an incorrect gasket in the incorrect place? That can block things that should not be blocked. I've run across all of these things, in so many combinations, over the years, that I can't remember them all. And most of them were the result of something I did myself. I had a newly rebuilt four banger one time, that had been running well, before it ate a rod bearing. I put it all back together, and fired it up, set the timing, and took it for a little spin around the block; everything was "hunky-dory". I decided to drive it to a business conference to give it a bit if break in, and the first hill I pointed it up, it almost quit running, it was breaking up so badly. Since I was in a suit and tie, I eased my way to the meeteing, and back home, and cussed everything in the world, the whole way. Next chance I got, I started looking, and lo, and behold; the plug wires were shot. They had not been shot before the thing broke, but apparently the handling of the distributor and wires during the rebuild, caused them to go bad. So, I try not to discount anything, anymore. Good luck.