Re: Topaz won't idle, poor mileage
If the code wasn't fixed, reconnecting the battery won't get rid of the code. Only when you fix the problem and reflash the system will the code stay away. I suggest a Tune up with new plugs & wires. A compression check on all the cylinders. Black soot generally means your burning oil, so worst case would be you have a piston ring worn. To cure the idle - replace the TPS and/or IAC sensors.
'11 Ram Quad Cab 4x4 SXT 5.7L HEMI (stock); 48,500m
'06 Pontiac G6 GT 3.5L 220hp; 64,000m
'12 Chrysler 200 Limited 3.6L 283hp; 28,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!