It however does not have issues maintaining the temperature when it’s not actually printing. I can set my hotend to 215 before beggining my print and it’s happy to sit there.
Other problems with it include under extrusion and extruder skipping, as it seems to have troubles pushing the filament out.
What does this sound like it could be? Does it sound like a blockage? Could a blockage cause temperature issues? I have already tried turning off the part cooling fan as I had a similar issue with that a while back but that has no made a difference it seems.
Check the entire thermistor cable as well as the plug connections for tightness. Preheat the hotend and then wiggle/bend the cable 1 inch at a time all the way back to the main board plug checking to ensure the recorded temp remains constant. (You can also do this with an accurate multimeter checking resistance across the unplugged thermistor if you don’t want the printer on while poking around.)
Those aggressive jumps sure look like a thermistor problem, but only when printing in motion, which screams bad cable/connection. Manufacturing errors happen.