A 52-year-old male has had cough, sputum production, and wheezing since childhood, often triggered by cold exposure and relieved by intravenous penicillin. He was symptom-free from ages 10-20 but had a severe attack at age 20, presenting with profuse sweating, cyanosis, orthopnea, and wheezes on auscultation, which resolved completely with IV theophylline and dexamethasone. Since then, he has recurrent nocturnal wheezing (>3 episodes/week) affecting sleep, with a PEF variability of 35%. Current exam reveals no crackles or wheezes on lung auscultation and a heart rate of 89 bpm. The most likely diagnosis is: