Paul wanted to be sinless. However God said His grace was sufficient.
Now let's work out what this involves. Remember, the writers of Scripture knew that unpacking the view would require supernatural help, require asking for the leading of the Holy Spirit, so expect the view to be complex and nuanced.
Paul knew that sinlessness was required in order to have a better resurrection, the resurrection of body, AS WELL AS THE SPIRIT. In order to save the body, he must subdue it, put to death the deeds of the flesh.
If he walked in the light, his faults would be revealed. If he confessed, agreed with what God's word revealed, God would be righteous and just, be obligated to fulfil His promise because of His just nature, His law abiding nature, not to default on His promise, but make Paul a blessing to the world, by cleansing him of that fault, so that he would be without blemish, an acceptable sacrifice in the sight of God, and so be able to share in what remains of Christ's afflictions.
However, in spite of repeated confession, the thorn in the side that had been given to prevent him from becoming proud was not cleansed. God said His grace was sufficient for Paul.
Sufficient for what?
Sufficient for the inheritance, being a blessing to the world.
Both in this life and at the end.
Because Paul was loyal, he was in God's good books, in His good graces.
Because of being in God's good books, he was IN Christ. Paul was really saved by grace, through faith. He was really receiving the inheritance, being a blessing through the world. Because of his weakness, his listeners knew it was not Paul who spoke words or did works, that confirmed God was with him, just as He had been with Moses, and so it was safe to let these anointed people lead them into safety, into rest, into Christ.
2 Corinthians 12:7Because of the surpassing greatness of the revelations, for this reason, to keep me from exalting myself, there was given me a thorn in the flesh, a messenger of Satan to torment me—to keep me from exalting myself! 8Concerning this I implored the Lord three times that it might leave me. 9And He has said to me, “My grace is sufficient for you, for power is perfected in weakness.” Most gladly, therefore, I will rather boast about my weaknesses, so that the power of Christ may dwell in me. 10Therefore I am well content with weaknesses, with insults, with distresses, with persecutions, with difficulties, for Christ’s sake; for when I am weak, then I am strong.
Sinlessness is the goal of sanctification.