Engine ran rough then was fine. Did it again and I pulled #1 wire from distributer cap and engine ran the same. Replaced wires, plugs, rotor and cap was fine for 1000miles. Same problem with #1 cylinder. Spark is good. Pulled plug and gas dripped off. Also gas coming out of exhaust. Repalced ignition coil, no change. All done on mechanic's advice. Told maybe map sensor? Easy fix. Question is why only #1 cylinder? Maybe vacum leak. Any ideas?