Do you mean P0300?
P0300 - Engine Misfire Detected
I don't see any error codes referring to misfire with cly 1-4.
Is this the only error you get? Have you had any major work done, such as
relaced the PCM or crankshaft? If the PCM or crankshaft is replaced, the the
crankshaft must be relearnd.
Have you tested the spark plug wires? resistance should be between 1.5k-15k
ohms. try replacing spark plugs and wires, if error still occurs, try
replacing coil packs
Try checking for vacuum leaks, often causes a high idle.

Thats all i can think of now.
hope that helps

Jeremiah