Tahoe misfire issues

[slam59]

I have a 1999 2door 2wheel drive Tahoe with the 5.7 vortex motor. I put new plugs and cap and rotor in it 3 months ago. Started getting rough idle a month ago off and on. Check engine light comes on and says two codes one for misfire the other for 02 sensor. Replaced sensor cleared codes and it ran and idled great. Next day on way home from work it idled badly again and check engine light comes on again. We figured we should have replaced wires. So last night wires replaced and used sea foam thru take booster line and it ran great. This morning oneaytowork light comes on again. What should I try next? Could another sensor be acting up? Or maybe the cap and rotor I put in a few months ago be a bad one? Don’t know what I should try next. Going to see what code comes up when I get home today. It’s been the p0300 or p0303 each time and even tough it idlers much better last night after installing new wires my friends snap on code reader shows a real time display of the cylinders firing and it showed 1 3 5 and 7 cylinders had minor misfires without causing the light to come on until I was driving it this morning