OBJECTIVES: I. Determine objective response rate, duration of response, and time to disease progression in patients with stage IIIB (pleural or pericardial disease) or stage IV non-small cell lung cancer treated with 10-propargyl-10-deazaaminopterin as first line or second line chemotherapy. II. Determine the toxicity of this drug in this patient population. III. Determine duration of survival in these patients. IV. Determine quality of life of these patients.