ar57

Can anybody give me a good guess about a problem I developed with my Galaxy (1998 Ghia, 2.3 petrol). Suddenly the engine is missing a beat, noise and power wise. I thought one piston does not fire. I replaced the 4 spark plugs; witch did not solve the problem. I tried to disconnect the spark plugs, one by one and listen how the engine sounds. I think I identified cylinder 3 as the culprit. I tested and verified that the cable from the Ignition Coil to the plug is ok. What options do I left with? Could the actual Ignition Coil being faulty? It seems to serve two plugs (2 and 3). Can it be faulty only for one plug only? Or am I completely barking on the wrong tree? Thank you for any advice or hint regarding this.