Tomas - as this is an international forum, can you post your questions in English so that all members can understand them please?
My translation of your question is:
Your engine has many hours up (how many?) and that you may have a problem with the injector pump due to problems on hills/slopes.[/]
What colour is your smoke?
Will your tractor reduce its speed when going downhill or does it speed up when the the revs are reduced?
Tom