Clutch/Transmission rattle

[SSGCracker]

Ok I apologize off the top if this is in a thread already but i didn't see it when I did a search. So I have 03 Mach with total mileage right at 203k. I bought the car at 180k and was informed that 20k prior the engine, transmission, clutch had all been rebuilt to ford spec. With thew interior being as flawless as it is and how well the car ran you would never guess that it could be over 30k. So everything has been great other than a couple minor issues where all of a sudden an O2 sensor went bad, then a check engine light for a MAF, and one for an idle air control valve, and sudden appearance of engine noise through the radio.

The issue that has me and most important is a strange rattling that I assume is transmission/clutch related. Every time that I press the clutch to the floor I get a rattling sound. It's loudest when first operating the car and steadily goes away the more it's driven and disappears almost completely to completely at times after a bit of driving. Once I let off the clutch it completely disappears. It is no worse or no better if the shifter is in neutral or any other gear.. Has anyone had this same issue and knows what it is or does anyone have any ideas of what it most likely is?