Dan, mine did the same thing a few weeks back. I first thought it was bad gas, but fuel treatment didn't help. I bought the truck three years ago, and other than plugs, points cap and rotor had not touched the engine, so I started in on replacing parts I figured needed done anyway. Rebuilt the carb, new fuel pump and filter, coil, plugs, wires. The cap and rotor looked good. Still same problem. New vacuum advance and vacuum line, no help. Pulled rocker cover and adjusted valves, some were too loose, some too tight. This helped some. Finally decided to replace cap and rotor. Now she'll run 50 plus with no problem, before 42 was max before she started wheezing. I feel silly for some of this, but for less than $200 at least now I know what I have. I even got brave and checked compression, not knowing how many miles are on the 54 engine she has, but was pleasantly surprised with good numbers. It was a process of elimination, be patient and you'll get er. John
