Engine Trouble

[Asterix]

I have a 2001 sportage that seems to be running on only two cylinders. I get P0300, P0303 and P0304 engine codes. I've changed the fuel filter, spark plugs, spark plug wires and one of the ignition coils. So far nothing has made a difference. Does anyone have ideas on what I should do next?

[hvac1000]

P0100 Mass Air Flow or Volume Air Flow Circuit Malfunction.
P0101 Mass Air Flow or Volume Air Flow Circuit Range/Performance problem.
P0102 Mass Air Flow or Volume Air Flow Circuit Low Input.
P0103 Mass Air Flow or Volume Air Flow Circuit High Input.
P0107 MAP/BARO Circuit Low Input.
P0108 MAP/BARO Circuit High Input.
P0110 A/T Circuit Malfunction.
P0115 Engine Coolant Temperature Circuit Malfunction.
P0116 Engine Coolant Temperature Circuit Range/Performance Condition.
P0117 Engine Coolant Temperature Circuit Low Input.
P0118 Engine Coolant Temperature Circuit High Input.
P0120 Throttle Position Malfunction - Circuit A.
P0122 APP/TPP Sensor Switch Low Input - Circuit A.
P0123 APP/TPP Sensor Switch High Input - Circuit A.
P0125 Insufficient Coolant Temperature for Closed Loop Fuel Control.
P0130 Oxygen Sensor Circuit Malfunction - Bank 1 Sensor 1.
P0131 Oxygen Sensor Circuit Low Voltage - Bank 1 Sensor 1.
P0132 Oxygen Sensor Circuit High Voltage - Bank 1 Sensor 1.
P0133 Oxygen Sensor Circuit Slow Response - Bank 1 Sensor 1.
P0134 Oxygen Sensor Circuit No Activity detected - Bank 1 Sensor 1.
P0135 Oxygen Sensor Heater Circuit Malfunction - Bank 1 Sensor 1.
P0136 Oxygen Sensor Circuit Malfunction - Bank 1 Sensor 2.
P0137 Oxygen Sensor Circuit Low Voltage - Bank 1 Sensor 2.
P0138 Oxygen Sensor Circuit High Voltage - Bank 1 Sensor 2.
P0139 Oxygen Sensor Circuit Slow Response - Bank 1 Sensor 2.
P0140 Oxygen Sensor Circuit No Activity detected - Bank 1 Sensor 2.
P0141 Oxygen Sensor Heater Circuit Malfunction - Bank 1 Sensor 2.
P0170 Fuel Trim Malfunction - Bank 1.
P0171 System too Lean - Bank 1.
P0172 System too Rich - Bank 1.
P0261 Injector Circuit Low - Cyl. 1.
P0262 Injector Circuit High - Cyl. 1.
P0264 Injector Circuit Low - Cyl. 2.
P0265 Injector Circuit High - Cyl. 2.
P0267 Injector Circuit Low - Cyl. 3.
P0268 Injector Circuit High - Cyl. 3.
P0270 Injector Circuit Low - Cyl. 4.
P0271 Injector Circuit High - Cyl. 4.
P0300 Multiple/Random Misfire detected.
P0301 Misfire detected - Cyls. 1-4.
P0302 Misfire detected - Cyls. 1-4.
P0303 Misfire detected - Cyls. 1-4.
P0304 Misfire detected - Cyls. 1-4.
P0325 Knock Sensor Circuit Malfunction
P0326 Knock Sensor 1 Circuit Range/Performance - Bank 1 or Single Sensor.
P0335 Crankshaft Position Sensor Malfunction - Circuit A.
P0336 Crankshaft Position Sensor Range/Performance - Circuit A.
P0340 Crankshaft Position Sensor Circuit Malfunction.
P0342 Crankshaft Position Sensor Circuit Low Input.
P0343 Crankshaft Position Sensor Circuit High Input.
P0400 EGR Flow Malfunction.
P0403 EGR Circuit Malfunction.
P0404 EGR Circuit Range/Performance Malfunction.
P0420 Catalyst System Efficiency below Threshold - Bank 1.
P0422 Main Catalyst Efficiency below Threshold - Bank 1.
P0440 Evaporative Control Malfunction.
P0441 Evaporative Control System - Improper Purge.
P0442 Evaporative Control System - Small Leak detected.
P0443 Evaporative Control System Purge Control Valve Circuit Malfunction.
P0446 Evaporative Vent Control Circuit Malfunction.
P0447 Evaporative Vent Control Circuit Open.

Now acording to KIA code you have misfire. You might want to check the connectors where the plug together. There are a few of them that can cause the trouble you are having. Also check the grounds on the car that can also caudse the problem. Now what was it doing before you spent all money to fix it?

[Asterix]

I haven't checked the grounds. The car vibrates at idle and is very close to stalling, although it rarely actually stalls once it's running. I replaced one coil pack and the vibration got slightly better but not much. I assumed, perhaps wrongly, that P0303 and P0304 referred to the 3 and 4th cylinders.