Breathing problems as you describe indicate either worn engine or blocked crankcase vent, hopefully the latter not the most fun of jobs so people rarely clean it. You will find it at the front of the car close to the dip stick, the centre bolt needs to be removed then you can take off the cover and clean it but it is not easy to access. If the vent is blocked I think that suggests that oil changes have been neglected so I would be tempted to use an engine flush and then fill with a high quality oil of suitable viscosity 10w40 or slightly thicker, avoid modern super thin oils as the engine wasn't designed to use them.