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.
Luck of the draw, could be bad out of the gate, my prusa mk3 had the exact same thing happen less than a month after running it. If you can, add a pinned connection, makes swapping thermistors super easy as a lot of places sell cartridges with microfit connectors.
When I had it happen it wasn’t always a problem, was only on certain movements and then it’d error on thermal runaway. I’d say change it anyhow as it’s simple to do and you eliminate a cause, best to start with the easy things.