What an odd assumption... the vehicle in question is nearly 20 years old...
As far as misfiring plugs showing up on anyones "test equipment" - nobody uses an ignition analyzer type scope these days... (disclaimer - Ford supplies us ignition test leads with the current VMM testing module - but techs are seldom directed to use the feature when reading the PC/ED). Occasionally we are directed to perform a coil "stress test". Setting up and performing the test costs more than simply replacing the coil as a diagnostic test step...
The new 6.2 gas engine may offer some interesting symptoms with it's dual plug arrangement.