You are facing a typical problem of fluctuating INR. This is usually for following reason:
Clotting factors are produced by liver
from Vitamin K. Warfarin
blocks the clotting factors produced in liver by competitively inhibiting uptake of Vitamin K. When your dietary Vitamin K goes up, the INR drops and when your intake is low, it goes up.
Now the solution is simple. Avoid eating foods rich is Vitamin K such as cauliflower, cabbage, green tomato etc. This will stabilize the INR. Then adjust the medicine dose to keep it around 2 to 2.5.
Recurrent pulmonary embolism
is a problem with blood vessels and not with lungs. A transplant wont be a solution. Investigate in to the cause of recurrent thromboembolism
and treat it along with warfarin.