Hi guys,
I had a temperature problem during the last days and finally found the solution for this. I just wanted to share this knownledge as this could happen to all of you out of nowhere…
My printer was printing fine but from the one to the other day my printer was always stopping ~layer #2 due to nozzle temperature malfunctions. I was printing with normal PLA and the nozzle temperature dropped from 220 to 205 and the print got automatically paused. After resuming this happened again and again. I reduced the bed temperature from 55 to 50 and it worked again. …at least for a while 
I was able to finish my print but with the next one the problem arised again and could no more be solved with my bed-temperature-lowering-hack.
So I did a firmware reset as the first layer never showed that problems and I thought about software issues. But this did not solve the problem.
Finally I disassembled the hotend and figured out that the thermal sensor was a bit loose. So I cleaned the entire hotend and added new thermal grease to the heater and the sensor. …and tataaa - the problems vanished as fast as they arised 
so whenever you experience temperature drop-downs beginning with layer #2 >> try this and it might solves your problem!
I think that the loose sensor (the thermal grease somehow reduced - that’s why I said this could happen to all of you out of nowhere) was moving too much and with increasing print speed (which begins with layer #2) there was not enough thermal flow to the sensor what was causing the temperature drops. I still don’t know how this is connected with my print-bed-temperature-hack but maybe there was more power available for the hotend when the bed temperature decreased.
Hope this helps someone else
BR,
B@sti