Ford friends, my 63 ford f100 longbed stepside factory 4wd with the 292 y block tends to start running a mite ruff once she's fully warmed up, sometimes the plug wires vibrate off or at Least loose on the dad gum washboard county roads where I live. Shell start cutting out wanting to stall while I'm hitting higher speeds so I have to downshift to keep the motor goin So's I can pull over to check the wires. Keep gettin a jolt from a wire or two when I tighten them running. Once tightened with a few burns off the manifold for good measure, she begins to run normal for a stretch then the sputtering and tail pipe popping resumes in all it's glory. During all this she idles fine. Does it sound like a top notch tune-up with HD plug wires protectedvp by a Heat shield as well as a timing check is in order. Compression checks out good and the shop supposedly tuned Er up. The vehicle count smoke at all. Sure love to hear from someone who might help me get Er squared away!
Chuck

 

If you have a pair of pliers, you could squeeze the end of the wire where it goes over the plug a little, making it fit tighter. as for the exhaust popping, the carb may be too rich causing the unburnt fuel to explode in the muffler. Or the timing could be some off, and you might want to pull the plugs and check the condition, as well as the inside of the dist cap, and points.

 

Still running points? Try a known good condenser. Known good, not necessarily new. Might try a bag of ice or freeze spray on condenser or ignition coil when it starts acting up. If the problem goes away, you've found it.