So I've been chasing a low RPM miss for a while and I'm stumped, so I'm turning to the experts. 1997 Cobra with 69k miles. All stock engine/exhaust with the exception of a Spectre air filter. When I got the car several months ago, I did a bunch of maintenance. New PCV valve, new plugs (autolite XP104), new plug wires (FRPP), fuel filter, air filter. Ran great. Ran great before I did all of the maintenance too, but it was all factory original, so I figured it was due. Recently, over the past few weeks, I've been getting a rough idle with an audible miss. It doesn't miss at idle when cold. Also, I get a low RPM stumble/miss under load. It will still stumble/miss when cold, though not as bad as when warm. Cruising is fine. It will stumble in gears 2-5 between 1500-3000RPM. Once the IMRC's open it screams clear to redline. Since this has happened, I've pulled and regapped the plugs smaller (from the original .054 to .047) thinking it wasn't sparking. I've tried to isolate the miss by pulling plug wires one by one and I can't seem to pin down any specific cylinder. I've listened to the injectors to make sure they're clicking steady and they all are. I've cleaned the MAF, IAC, EGR valve, IAT sensor. I did the seafoam through the PCV and let it sit. I did get a code initially when it started this which was a code for the passenger side o2 sensor. I replaced both upstream O2's with motorcraft sensors. That seemed to take it away temporarily (could've also been in my head), but it came back quickly. No CEL since. It didn't seem to coincide with any of the aforementioned maintenance. Also, it does seem to have a slight smell of a clogged cat and it does have a rattle at low RPM (like just off idle when backing it out). All of the cat heat shields seem to be tight. I'm left thinking it might be fuel pump (though I would think fuel starvation would be more prominent at higher RPM than lower) MAF (maybe the sensor itself is bad and cleaning won't help) Clogged cats (I would also think this would be more prominent at higher RPM) Thoughts everyone? I've done hours of research and it seems like the people with similar symptoms never respond back with a resolution.