I was a flight mechanic on a Bell HTL-1 (B-47) flying from Miami to New York. We were over a small town in Maryland and our engine started to run rough. We landed in a schoolyard across the street from a gas station. I pulled the plugs and went to the gas station and used their spark plug cleaner. I reinstalled the plugs and fired the engine up and it ran smoothly. With that, we lifted off and continued our journey. The gas station proprietor gave the pilot and myself a couple of Coca Colas but no coffee.