Paul called himself the chief of sinners and that he knew what was right and still did wrong.
As for Romans 7:14-24 that sounds like Paul is struggling with sin as a Christian. This kind of reading has to ignore all of the context that surrounds this passage. Actually Paul is talking as a Pharisee before he became a Christian in Romans 7:14-24. Romans 7:6 says we are to serve in newness of spirit and not in the oldness of the letter. The oldness of the letter is the 613 Old Testament Commands or the Torah. Romans 8:3-5 says,
3 "For what the law could not do, THAT IT WAS WEAK THRU THE FLESH (i.e. Saul's or Paul's past struggle as a Pharisee with sin) God sending his own Son in the likeness of sinful flesh, and for sin, condemned sin in the flesh:
4 That the righteousness of the law might be fulfilled in us, who walk not after the flesh, but after the Spirit.
5 For they that are after the flesh do mind the things of the flesh; but they that are after the Spirit the things of the Spirit." (Romans 8:3-5).
For there are TWO Laws mentioned in Romans 8:2. The first one is a New Covenant Law and the second is an Old Covenant Law. The Law of Sin and Death is Old Covenant because you could be put to death physically by not obeying it. Keeping the NT Law of the Spirit of Life in Christ Jesus sets us free from the Law of Sin and Death. So it is not law that is bad in general. It is knowing which Law to follow. For Hebrews 7:12 says the Law has changed.
Also, Paul says we are sold under sin in Romans 7:14 and yet in Romans 8:2 he says he is free from sin. So unless Paul is contradicting himself he is speaking from two different perspectives.
Also, Christians do not normally ask the question: "Who shall deliver me from this body of death?"
Did Paul forget who Jesus was? Surely not. Paul was speaking from his experience as a Pharisee in Romans 7:24. Then in Romans 7:25, Paul switches back to talking as a Christian again.
You said:
He was speaking present tense. Jesus said "the spirit is willing but the flesh is weak."
Jesus also told two people to “
sin no more” (John 5:14) (John 8:11).
If it was not possible for a person to “
sin no more” than Jesus would have been lying. But that's not possible because Jesus is God and He cannot lie. Jesus is the way, the truth, and the life (John 14:6). Jesus would never steer us in the wrong direction.