Terri, thank you. I have wondered if the heat from baby bottle sterilizing or boiling water in Instant pot was what was causing the problem. After getting the Pari Trek S (palm size) and foaming also occurred then I started thinking it might be the sterilizing method that was the problem. My neb cups are are Pari LC Sprint. (blue screw on top with handle and blue flap on mouth piece. Has a center removal cone. Is that the type you have.
I will also order a Vios Green. Good to have a backup.