OK so let's say as far as you know you don't have any, the temptations are purely coming from thoughts in your head/past history from before one's conversion?
You're describing the same thing that we all deal with - and we all will deal with it till we draw our last breath. Even Hermits who went to live in caves to rid themselves of such thoughts from past history dealt with this, many of them left their cave and returned to sin. "As fire testeth iron, so doth temptation the upright man" says Thomas A Kempis.
Pray 15 decades every day, get in the habit of mental prayer, fast and abstain as often as you can, be extra attentive at Mass and do your 5 First Saturdays, doing these things and more will help to keep you in the state of grace and grow in that state. Go to confession weekly, or every other week whether you need it or not. In time, you won't need it but will reap the graces which only help.