This is not bad grammar, but a potent question: “Who is the ‘I’ of Romans 7?” There are several possibilities and we’ll do well to get these in mind before we look at his chapter.
First, the “normal Christian.” In other words, Christians at one time or another find themselves struggling with the power of grace because they rely on Torah. Both Cranfield and Dunn maintain something like this; but, as NT Wright says, such a view, which implies that the Christian life is an ongoing struggle with the Torah, has been freed from the Torah and does not live in sin.
Second, Paul’s “autobiography.” In other words, this struggle with the Torah is Paul’s own story of how he experienced the Torah before he came to Christ. As such, it is really only the story of Paul.
Third, Adam’s “experience before the Fall.” In other words, Romans 7:7-12 best fits only the experience of Adam: I was alive before the commandment came… etc.
Fourth, the human “existential” view: this passage is about no one in particular but everyone in general. All humans struggle morally; all humans can find release through God’s Spirit; no human can find release through the Torah.
Fifth, and the view maintained by more and more today, the “I” of Romans 7 is “Israel” under the Torah before Christ, which Paul embodies by using “I.” Thus, the passage is not about you and me and our individual “I” (Ego) as we struggle, but a literarily potent way of using “I” for Israel in order to dramatize Israel’s experience under the Torah. That time, as 7:1-6 says, has come to an end in Christ. For those who are “in Christ” that struggle is now over.