Ozzie 1/9/2015Did your engine light come on and if so what code did it give you? I have a 2002 Mercury Sable 3.0 GS and once in a while it would give me P0301 or P0305 and then once in a while it would give me P0300 Random Misfire or P0171 & P0172 Bank 1 and Bank 2. I knew it was not my plugs or wires cause I had the engine tuned up and changed wires so I checked Coil and there was my problem. By the way it only did this on idle cause once I had it at high idle it would run perfect. So check your coil.