Spark at the plugs+ gasoline is going to do something even if it's wrong. I would invest not one cent into anything until the system has been diagnosed.
Pull #1 spark plug. Hold finger on hole to detect escaping pressure. Tap engine over. Until you feel pressure escaping. When you feel cylinder pressure. Stop. Look at timing marks on shield overtop the viration damper and correlate that to the big notch that runs across the damper. Is the mark anywhere near the -12 to ATDC shield markings? If not
Then it could be a stripped nylon tooth on the camshaft timing chain gear. A COMPRESSION TEST with a gauge is next on the list. But usually when cam timing goes it does not return and when you crank the engine it sounds like a washing machine.
A failed roll pin in the distributor drive gear can allow the gear to wobble back and forth throwing ignition timing for a loop. But tailpipe explosions and and popping back through the carburetor are usual when that happens.
Ignition timing way the hell and gone out of range can cause an engine to play possum. In this case a bad distributor pickup coil or a reluctor gear that broke loose can be the culprit. The pickup coil is the boomerang shaped black plastic part with flat electrical connector prongs on both ends.
The run OK run bad symptoms you describe sure point to an intermittent distributor issue. Unless a carbon track on the cap or within the rotor goes diectly to ground the engine will fire. Maybe misfire but not play possum. A bad coil can be intermittent too.
Long distance troubleshooting is a real turkey. If the cap and rotor are carbon tracked anyway replace them -you have nothing to lose. Next is the distributor pickup module. From there it's verify distributor and timing gear time. Keep checking the spark at the plugs as you troubleshoot components. If it is constant keep digging. Tip I have had more out of the box failures with Standard and Blue Streak brand than all others combined. Overpriced junk. Wish I could gear the engine and see the components. A bad HEI module connector can screw you up too.
