Question: Guidance for getting off of 150 mg Immuran a day (after several years)

I have Primary Sjorgren's and was put on Imuran (after a trial period in which my rheumatologist explored other medication possibilities) because i developed a so-called, I suppose, Sjorgren's lung and was diagnosed with interstitial lung disease and some asthma. I have had bacterial pneumonia at least twice in the past couple years (yes, I have had the pneumonia vaccine). I have cough (off and on) and sometimes shortness of breath. I also have osteoporosis, osteoarthritis, and secondary pulmonary hypertension when the asthma kicks in. For a while I was on oxygen 24/7, but I responded so well to diet, exercise, and Imuran I was able to go off of it entirely and my normal oxygenation rate stays right around 94. I found Furhman and very much believe in his diet but am afraid of taking the big step of going off Imuran although his books say his diet can do it. My pulmonologist and rheumatologist will discuss this same question and my pulmonologist has shared with me the desire to lower or get me off the Imuran but he realizes/knows the possible hazards of it not being the principle reason for my improvement. I have lost over 100 lbs and held it for three years and have moved from a sedentary lifestyle to one with regular exercise (walking and recumbent bicycle.) I decided to reach out to your community and think about this question, as well, to the best of my ability. I am also rereading Furhman. Thank you for exploring this with me. Oh, I do have a heart stenosis which I have had for some 60 years but it causes me no known issues and has been checked out frequently.
Medications for hypertension (under control): Losartan, Lovazza; I was on Furosemide for edema but have recently discontinued it. Because of the Furosemide I was on potassium (Klor-Con). I take a baby aspirin, a multi-vitamin, and calcium and vitamin D. I also take CYMBALTA for arthritic pain primarily.