97 Metro miss fire

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???

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...

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