when warmed up fully idle will back off below 1000 looks 8-900rpm and idle stays solid but car now begins a low popping noise almost as if fuel has water... But tried a reputable pump and filled and no change. Examined plugs and wires no signs of damage/irregular operation. Possible coil wires or coil it self? othere then that car drives normal and has power as usual car is 2004 aveo 140k km. Any ideas pointers would help!