The instinct behind the question is honorable: you want the actual Jesus, not a later interpretation of him. The problem is that Jesus himself refused to be a standalone authority, and the mechanism that delivered his words to you is the same one that delivered Paul's.

1. Jesus treated Scripture as binding. He said, "the Scripture cannot be broken" (John 10:35), and "not the smallest letter or stroke of a letter will pass from the Law" (Matthew 5:18). On the road to Emmaus he interpreted "Moses and all the Prophets" as being about himself (Luke 24:27). A Jesus-only canon cannot even be consistently Jesus-only, because the Jesus of the Gospels is saturated in the rest of the Bible and insists on it.

2. He promised more revelation after he left. "The Helper, the Holy Spirit, whom the Father will send in my name, he will teach you all things and bring to your remembrance all that I have said to you" (John 14:26). And, more pointedly, "I still have many things to say to you, but you cannot bear them now. When the Spirit of truth comes, he will guide you into all the truth" (John 16:12-13). If that promise is false, the Gospels misreport Jesus. If it is true, expecting more teaching after the resurrection is obedience, not addition.

3. He authorized specific men to speak for him. "Whoever listens to you listens to me, and whoever rejects you rejects me" (Luke 10:16). He commissioned the apostles to teach "all that I have commanded you" (Matthew 28:20) and told them, "As the Father has sent me, even so I am sending you" (John 20:21). Paul's apostleship is claimed on the same basis — a direct commission from the risen Christ (Galatians 1:11-12; Acts 9:15).

4. Peter calls Paul's letters Scripture. In 2 Peter 3:15-16, Peter refers to "our beloved brother Paul" and says that in his letters "there are some things in them that are hard to understand, which the ignorant and unstable twist to their own destruction, as they do the other Scriptures." That places Paul's letters in the category of Scripture, on the testimony of an apostle who knew Jesus. Be fair: some critical scholars dispute that Peter wrote 2 Peter. Even so, the book is early and the judgment is not a fourth-century invention.

5. The same channel delivers both. The red letters reach you through manuscripts copied by the church, selected into a canon by the church, and translated by committees. If that chain is trustworthy enough for Matthew and John, it is trustworthy enough for Romans. You cannot accept the channel for Jesus and distrust it for Paul without a reason specific to Paul — and "I don't like his theology" is a preference, not a textual finding.

6. Paul's gospel is the same gospel. Paul did not invent a religion; he received one. "I delivered to you as of first importance what I also received: that Christ died for our sins... that he was raised" (1 Corinthians 15:3). He argued with Peter to his face over table fellowship (Galatians 2:11-14) — which is not the behavior of a man inventing a rival faith, but of one fighting for the same one. And the Jerusalem council ratified his mission to the Gentiles (Acts 15).

7. Turn: the red-letter canon is self-defeating. To have "only the words of Jesus," you must know which words are his — which requires trusting the church's canon, the manuscripts, and the copyists you were trying to bypass. And when you get there, the Jesus you find commands you to listen to the apostles. The red-letter approach does not escape tradition; it silently depends on it and then discards the parts it dislikes.

8. Development is not contradiction. Jesus implies the Trinity at baptism and in the Great Commission; Paul states it. Jesus speaks of his death as a ransom; Paul explains what that accomplished. Jesus inaugurates the kingdom; Paul works out what it means that Gentiles are included without becoming Jews. That is what it looks like when an event is thought through, and it is what the New Testament openly claims to be doing.

If you want Jesus, you cannot get him without the men he sent, because he deliberately left it that way. The New Testament is not Jesus plus an unrelated appendix; it is the apostles explaining, in writing, what Jesus did.

Sources: Michael J. Kruger, Canon Revisited; Richard Bauckham, Jesus and the Eyewitnesses; N.T. Wright; Daniel B. Wallace.