Following are the codes I'm getting. Should I start with coil's, plugs, wires???? What's the most common issue with these misfires?

P0300: Random/Multiple Cylinder Misfire Detected
P0303: Cylinder 3 Misfire Detected
P0305: Cylinder 5 Misfire Detected
P0306: Cylinder 6 Misfire Detected
P0455: Evaporative Emission Control System Leak Detected (gross leak)

 

Is start with plugs and a valve adjustment, coils are know to go bad too. I've seen tight exhaust valves if it has over 100,000 just do it.

 

I have the same vehicle and the same problem.

Yesterday the car was fine and today (all of a sudden) I have
P0300, P0303, P0305, and P0306 misfire codes.

I did not get the other code though but its kind of strange that we got the same exact cylinder misfires.

Is there anything in common with these particular cylinders?

Not sure where to start... O2 sensor? Pre-CAT? Fuel injectors?

The Saturn seems to be running ok and I don't really feel a misfire...

Any advice would be helpful.

Thanks very much!

Loren