It is no more I that do it - This is evidently figurative language, for it is really the man that sins when evil is committed. But the apostle makes a distinction between sin and what he intends by the pronoun "I". By the former he evidently means his corrupt nature. By the latter he refers to his renewed nature, his Christian principles. He means to say that he does not approve or love it in his present state, but that it is the result of his native propensities and passions. In his heart, and conscience, and habitual feeling, he did not choose to commit sin, but abhorred it. Thus, every Christian can say that he does not choose to do evil, but would wish to be perfect; that he hates sin, and yet that his corrupt passions lead him astray.

But sin - My corrupt passions and native propensities.

That dwelleth in me - Dwelling in me as its home. This is a strong expression, denoting that sin had taken up its habitation in the mind, and abode there. It had not been yet wholly dislodged. This expression stands in contrast with another that occurs, where it is said that "the Spirit of God dwells" in the Christian, Romans 8:9; 1 Corinthians 3:16. The sense is, that he is strongly influenced by sin on the one hand, and by the Spirit on the other. From this expression has arisen the phrase so common among Christians, in-dwelling sin.

Romans 7:17 Parallel Commentaries

The Fainting Warrior
Now, humble Christians are often the dupes of a very foolish error. They look up to certain advanced saints and able ministers, and they say, "Surely, such men as these do not suffer as I do; they do not contend with the same evil passions as those which vex and trouble me." Ah! if they knew the heard of those men, if they could read their inward conflicts, they would soon discover that the nearer a man lives to God, the more intensely has he to mourn over his own evil heart, and the more his Master …
Charles Haddon Spurgeon—Spurgeon's Sermons Volume 5: 1859

There are Therefore in us Evil Desires, by Consenting not unto which we Live...
20. There are therefore in us evil desires, by consenting not unto which we live not ill: there are in us lusts of sins, by obeying not which we perfect not evil, but by having them do not as yet perfect good. The Apostle shows both, that neither is good here perfected, where evil is so lusted after, nor evil here perfected, whereas such lust is not obeyed. The one forsooth he shows, where he says, "To will is present with me, but to perfect good is not;" [1875] the other, where he says, "Walk in …
St. Augustine—On Continence

Its Source
Let us here review, briefly, the ground which we have already covered. We have seen, first, that "to justify" means to pronounce righteous. It is not a Divine work, but a Divine verdict, the sentence of the Supreme Court, declaring that the one justified stands perfectly conformed to all the requirements of the law. Justification assures the believer that the Judge of all the earth is for him, and not against him: that justice itself is on his side. Second, we dwelt upon the great and seemingly insoluable …
Arthur W. Pink—The Doctrine of Justification