Seemingly unsolvable stringing/heat creep issues  

Seemingly unsolvable stringing/heat creep issues

Hi all. I've been having some particularly bad stringing in my MK3S+ for the past three weeks and I've been tearing my hair out quite literally in trying to fix this. Whenever I unload my filament, regardless if it's 175 - 215C, it strings and chunks inside the extruder, and sometimes I have to open the idler gear door to remove those big chunks. I think I've isolated it to heat creep but nothing I do seems to have any positive effect.

I've been using the same filament that I've been printing string-free for a year at the same temperature at 195C so I know it's not the filament or print temperature. I replaced the thermistor and heat cartridge to no effect. Then I replaced my entire hotend with a fresh E3D V6, no change. This is a kit I've had to assemble, and I followed all the steps and think I've assembled it properly. Then I've found the part file of the extruder fan piece, the one that holds half of the heatsink fan and also the part cooling fan, and modified it to give it a much less steep angle for the air to approach the heatsink for better airflow, that still did not work. My most recent change is swapping the stock Noctua fan with a higher RPM Sunon fan. As I've read, the Noctua reaches about 5000 RPM and the Sunon should break 7000 RPM easily. But interestingly, the Noctua would run at about 4,100 RPM during prints and this new Sunon fan runs at 2,700 RPM. Of course, there is no change to the stringing and the chunking in the extruder on unload. I've looked up the firmware for the MK3S+ and it seems like the heatsink fan is automatically set to max speed? So I'm incredibly confused why the Sunon fan is running at a third of its rated speed. It's a 5V fan the same as the stock fan.

Somebody please tell me it's much simpler than this. I'm at my wit's end with this problem and I just want my great printing experience back. I feel like I've tried everything.