oil leaking from breather

2 breathers? there is your possible issue. Make one of those breathers a hose to the low pressure air cleaner. You need forced circulation (can I call it positive crankcase ventilation?) in there to rid the oil of acids and prevent coking. You can even run a standard PCV valve as it does nothing at idle and nothing at WOT, only venting during part throttle cruise or a header evac. If you choose the evac, run it through a catch can to lessen a black film all over the rear of the car.