What kind of hotend are you using? I had a lot of problems of seemenly spurious jamming problems with a bowden E3D hot-end. I tried new cleaning, new nozzles, higher temps etc and finally nailed it down to too much retraction (S3D advised 8 mm for my delta rostock max clone). The filament would be retracted, be pulled up too far, and then jam in the cooler parts of the hotend. With higher melting filament like ABS this happened sooner than with PLA. This gave a jam which even my Bondtech feeder could not overcome (it has 17 KG pulling/pushing capability, it just pulls snagging filament off the reel with ease and without hickups in the printing) . E3D specifies at least (much) less than 5mm.