Mea, it''s pretty tough to be helpful when you don''t even tell us what type of stove you are using. LPG? Kerosene? CNG?
Most ovens have no thermostat so consider whether that applies to your stove or not. If LPG fueled, a very common issue is the slow constriction of crud that occurs in the orifice of the burner. (Not all LPG is spotlessly clean, and sometimes it is ladeled with compressor oil from a tired compressor). Consider removing the orifice and running a very thin needle thru it to ream it out. If you have manual, it will dissuade you from doing this since the tendency is for folks to enlarge the hole dimensions. Bigger hole, poorer performance. But with care, I haven''t found this to create a problem the several times I''ve had to do it.