1997 Ford Expedition 4.6L P0301 Random Misfire: Symptoms, Diagnosis & Fixes

My 1997 Ford Expedition XLT 4x4 with a 4.6L engine is experiencing intermittent rough idling and misfiring, indicated by the Check Engine Light blinking (P0301). The issue occurs randomly—sometimes only on startup, and other times while driving—and the engine runs smoothly at first before gradually becoming rough. When the misfire happens, the exhaust sound changes noticeably, making it both frustrating and embarrassing. I replaced all spark plugs and wires six months ago with Bosch double platinum components in June 2008. The problem began recently around New Year's 2009. I’ve tried removing a Hypertech performance programmer (which I had used for a few weeks prior), but after switching back to stock settings, the issue persisted. The symptoms appear every other start-up and often worsen during driving. When the engine runs well initially, it typically starts misfiring shortly after. Given that the problem recurs intermittently and affects performance, I suspect either a faulty spark plug or ignition coil. I’m considering testing each cylinder by swapping plugs to see if the misfire follows—this could help isolate whether the issue is with a specific cylinder. I’ve also heard that Bosch plugs are sometimes recommended for Ford vehicles to prevent coil damage in coil-on-plug systems, though this is anecdotal. Does anyone have experience with P0301 on a 4.6L Expedition? Any suggestions for diagnosis or fixes? Will Holland