A crude but effective plug wire test is to spray the wires with a fine mist from a squirt bottle of water as the car is at idle..if they are bad ., it will skip right away.
Another is when the condition comes back, coat all the plug wires with WD40 and wait 5 min..if it clears up..bad plug wires
The problem usually shows up on rainy/humid days..the WD is a moisture
displacement...Original wires were solid core, so you may want to check what was put on there as a replacement. They may have used silicon resistor wires. The spray test will show them right off the bat.

The caps and rotors will be evident when you look at them

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A Dalton