.pss Simulation Results Vary in Different runs (Cadence)

I am simulating an amplifier using .pss in Sprectre. The output waveform has different amplitudes in different .pss runs.

These are the settings that I simulated with:

- errpreset (Accuracy): conservative
- tstab is long enough for the circuit to settle
- Integration method: default/gear2/gear2only
- maxperiods: default(20)/50

Any suggestion to get consistent results?

Thanks.