97 Metro miss fire

[chungne]

I have a 97 Metro with 1.0L eng. I keep getting the check engine light and fault code P0303 ( #3 cyl miss fire). This only occurs with the air conditioning on. The fault goes away after several starts without the a/c on. It idels rough with the a/c on but runs fine with it off.

I have changed plugs, plug, wires, rotor and cap. It car has approx 90k.
Anyone have any ideas???

[cpunet]

Check to see if you have an AC idle adjust valve like the 94 metro with AC. This is to adjust for engine load with AC, etc...

[chungne]

I did a compression test...no comp. cyl #3....burnt exh valve.